Im so freaking confused and stupid help me

- anonymous

Im so freaking confused and stupid help me

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- anonymous

All of the questions are based off of this word problem:
efren leaves home at 9am and walks 4 mph. his bro greg leaves 1/2 hr later and runs 8.5 mph in the same direction as efren. predict the time at which gred will catch up to efren

- anonymous

write an expression for the distance of greg's travels per hour let h stand for time in hours!

- anonymous

write an expression for the distance efren travels per hour plus the distance he will have traveled when greg leaves the house

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## More answers

- jim_thompson5910

if greg runs at a speed of 8.5 mph and he runs for h hours, how far will he run?

- anonymous

i dont know

- anonymous

im really stupid no joke when it comes to math

- jim_thompson5910

you're not stupid, you just need more practice

- jim_thompson5910

say he ran for 1 hour
how far would he get?

- anonymous

8.5 miles?

- jim_thompson5910

good, in 2 hours he will go ____ miles

- anonymous

17

- jim_thompson5910

how did you get that

- anonymous

8.5 x 2

- jim_thompson5910

so in 3 hours, he will run 8.5 x 3 = 25.5 miles
so in 4 hours, he will run 8.5 x 4 = 34 miles
....
in general...
if he runs h hours (some unknown amount of hours), then he will run 8.5 x h or just 8.5h miles

- jim_thompson5910

so if d = distance traveled, then
d = 8.5h

- anonymous

oh okay so it says write an expression but im confused on how to write one

- jim_thompson5910

ok so you'll just write 8.5h

- jim_thompson5910

8.5h is the expression
d = 8.5h is the equation

- anonymous

what about the other expression i have to write for efren

- jim_thompson5910

keep in mind that greg started 1/2 hour later than efren

- jim_thompson5910

so you have to account for that

- anonymous

oh & it says plus the distance he wil he will have traveled when greg leaves

- jim_thompson5910

let's assume they both start at the same time (9:30 am)
if efren walks at 4 mph and he does this for h hours, then he will walk a total of 4h miles

- anonymous

so would it be greg leaving at 9:30??

- jim_thompson5910

but this isn't the whole story because efren leaves at 9:00 am instead of 9:30 am
so he's got a 1/2 hr head start

- anonymous

okay

- anonymous

but i dont know what the distance formula is either thats one of the questions

- jim_thompson5910

so you have to add in the fact that he walked some additional distance in that half hour where he got the head start
if he walked 0.5 hours (1/2 hr) at a speed of 4 mph, then he would have walked 4*0.5 = 2 miles

- jim_thompson5910

distance formula:
distance = rate x time
d = r x t
d = rt

- jim_thompson5910

rate is known as speed

- anonymous

oh yeah i remember that lol

- anonymous

so he walked 2 miles??

- jim_thompson5910

yes in that half hour where he got the head start

- jim_thompson5910

so he walked 2 miles in the first half hour
then he walked an additional 4h miles after 9:30 am

- jim_thompson5910

in total, efren walked 2+4h or 4h + 2 miles

- anonymous

so what expression would be for efren plus the distance he would of traveled when greg left

- jim_thompson5910

4h + 2

- jim_thompson5910

4h is the amount he traveled when greg left
2 is the amount he traveled when greg was still at home

- anonymous

oh i see, sorry ive been up all night doing this and im annoyed and fed up :(

- jim_thompson5910

thats ok

- jim_thompson5910

to find out when the two will meet, you just set the two expressions equal to one another

- jim_thompson5910

8.5h = 4h + 2
and solve for h

- anonymous

so the next question is weird it says write an equation setting the distance expressions in steps 3 and 4 equal

- jim_thompson5910

yep you want to find out when the two will walk the same distance (ie find out when/where the two will meet)

- anonymous

could you help me figure that out ill try to do most my self

- jim_thompson5910

well you see how i got 8.5h = 4h + 2 right?

- anonymous

yup!

- anonymous

you added the time he waited to the expression

- jim_thompson5910

ok great, subtract 4h from both sides
8.5h = 4h + 2
8.5h - 4h = 2
4.5h = 2
what's next?

- anonymous

4.5 = 2 - 2 ?

- jim_thompson5910

4.5h is the same as 4.5 x h

- jim_thompson5910

how do you undo multiplication

- anonymous

OH! :) I know!!
4.5h/4.5 2/4.5

- anonymous

you divide 2 by 4.5

- anonymous

am i right?

- jim_thompson5910

you are correct

- jim_thompson5910

so h = ??

- jim_thompson5910

2/4.5 = ?

- anonymous

h = 0.4 repeating (so line over the 4)

- jim_thompson5910

so that's the rough approximation of how many hours it will take (after 9:30) for the two to meet

- jim_thompson5910

and for the two to travel the same distance

- jim_thompson5910

convert to minutes to get:
0.444*60 = 26.64
so it will take about 26.64 minutes

- anonymous

thank you very much for helping me i wish i was as smart as you i struggle just to keep my B- average

- jim_thompson5910

I'm sure you'll do fine, just keep your head up and keep practicing

- anonymous

thank you jim have a nice day!

- jim_thompson5910

you're welcome

- jim_thompson5910

you too

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