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Can someone explain this for me step by step? Abby rows 10 km upstream and 10 km back in a total time of 3 hr. The speed of the river is 5 km/h. Find Abby’s speed in still water. @mark_o.

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You found me lol
yeah im here now lol :D |dw:1354646559750:dw|
she row from starting point A to B then from B to A that is time from A to B + time from B to A = 3 hours

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Other answers:

time Tab + T ba = 3 (1) but distance d=velocity x time,. therefore t=d/v dAB dBA ------ + ------- =3 but distances dBA=dAB=10 km v v 10 10 ------- + ------ =3 v v but note that velocity of river is v=5 km/hr for upstream v= v+5 10 10 for down stream v= v-5, therefore ------- +------ = 3 v+5 v-5 you can algebra now ion finding v=?
i mean you can do the algebra now from this point ... :D
ummmm I am stuck
I am sorry lol
10/(v+5) + 10 /(v-5) =3 10(v-5) + 10(v+5) ------------------ =3 (v+5)(V-5)
do multiplication and addition to simplify the numerator and the denominator..:D
give me a sec
wow i suck cause I am lost
the v is throwing me off
10 10 -------- + ------- = 3 (v+5) (v-5) ? ------------------- =3 (v+5) (v-5)
for the further left, that is (v+5)(v-5) -----------= ? then mult by 10 (v+5)
then on the mid of it (v+5)(v-5) -----------= ? then mult by 10 (v-5)
10(v-5) + 10(v+5 ------------------- = 3 (v+5)(v-5)
ok give me a sec and let me figure this out
multiply the numerator then do addition on the denominator multiply them also
is that right
hhm where did you get 10-5 and 15+5 from? it should stay as 10( v-5)=? and 10(v+5)=?
10-5=5 AND 10+5=15
I just want to understand it
I guess you didn't like my explanation
no i asked you a question and you left
I just hate math and it takes me awhile to get it together
Well, I just answered your question
I left the room to help someone else with their question, but you should not assume that I had left.
it should stay as 10( v-5)=? and 10(v+5)=? 10( v-5)= 10v -50 is it ? and 10(v+5)= 10v +50 is it ?
ahh you have posted this before..yeah @andjie when we start coaching you dont assume that we had left .. :D
Thank you I am sorry
@mark_o. I am convinced you are doing this the hard way.
and for the denominator (v+5)(V-5)=?
haha i know..:D im sorry @Hero ...:D
Go check out my solution
where is that? lol... :D
I'll do anything to avoid a quadratic equation
Besides, I don't like when you get to a result where you have two solutions but have to discard one of them because it is negative.
i think andjie is just doing the refresher thing now.. to recall everything .. that was 7 years ago ? @ andjie?
9 almost ten years ago
wait I just had my high school reunion so it was 10 years ago lol
She's probably 28 years old
wow, almost 10 years ago? hmmm yeah this is a good refresher to you ... :D
I just posted a link to the solution
hhhm i cant open it, dont know why @Hero
I understand this better @hero hopefully I can do more like this
d = rt and let r = b ± w b = speed of the boat w = speed of the water current t1 = Upstream time t2 = Downsteam time 10 = 5t 2 = t1 t1 + t2 = 3 2 + t2 = 3 t2 = 3 - 2 t2 = 1 Upstream Formula d = rt1 d = (b - w)t1 Downsteam Formula: d = rt2 d = (b + w)t2 b - w = 5 Upstream 10 = 2(b - w) Downsteam 10 = (b + w) 10 = 2b - 2w 20 = 2b +2w 30 = 4b 30/4 = b 7.5 = b 10 = b + w 10 = 7.5 + w 10 - 7.5 = w 2.5 = w Therefore The speed of the boat was 7.5 km/h
ok this is good,, directly for the solutions and answer.... ;D
you did really avoid the quadratic equation .. :D
You guys are just too smart for me
I usually find ways to avoid it.
It's a personal goal of mine
ok that is very good.... and andjie can copy this one to study and do for a second solution or alternate solution..........:D
Thank you @mark_o. you always look out for me
Well, back to watching Smallville. I'm trying to get to the end of the 10th season and it's taking forever.
Have fun and thank you for your help
ok YW,, tc now and have fun solving..........:D
thanks for doing the alternative solution, that was a good one :D @Hero...............:D
You're welcome. I have plenty alternative solutions up my sleeve.
If you need an alternative solution, cite me.

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