## anonymous 3 years ago 1.A local bank has a debit card that gives a $3 reward each month you use your card for$50 or more in purchaces. Write an equation relating rewards earned,y, to total monthly purchaces, x. Give the domain of this function. 2. A local credit union has a debit card that rewards 3% of your total monthly purchases. Write an equation relating rewards earned,y, to total monthly purchases, x. Give domain of this function.

1. anonymous

the second one is easiest i think you get 3% of your monthly purchases, so if you call your monthly purchases $$x$$ then you get $$y=0.03x$$

2. anonymous

it has no lower limit, so i would say the domain is $$(0,\infty)$$ or "positive numbers"

3. anonymous

Honestly, any input would be appreciated. I'm totally clueless!

4. anonymous

this is not quite accurate, since you cannot spend say $$\pi$$ dollars so maybe the domain is positive integers

5. anonymous

how fancy is this math class?

6. anonymous

maybe you can get away with saying "positive numbers"

7. anonymous

It's just Algebra 1

8. anonymous

okay so you probably don't have to be so picky for the second one you can use $$y=0.03x$$ and say the domain is positive numbers

9. anonymous

for the first one, it is really $y= \left\{\begin{array}{rcc} 0 & \text{if} & x <50\\ 3& \text{if} & x \geq50 \end{array} \right.$

10. anonymous

but that might be too fancy as well, so maybe you can just say $$y=3$$ if $$x\geq50$$ or maybe even just say $$y=3$$ and the domain is $$x\geq 50$$

11. anonymous

Okay, thank you so much!! I've been stuck on math problems all night. I still have 3 more to go :(

12. anonymous

are they hard?

13. anonymous

14. anonymous

I'll type it here, if that's alright

15. anonymous

16. anonymous

1. Abigail orders a large 2 topping pizza for $14 and a medium 1 topping pizza for$10. If all coats of a medium pizza are 80% of a similar large pizza, find rhe price of a large plain cheese and the cost of each large pizza topping.

17. anonymous

costs*

18. anonymous

whoa this is going to take a second not too long though

19. anonymous

You don't have to do it if you don't want to! I understand.

20. anonymous

oh no we can definitely do this for sure

21. anonymous

Alrighty, thank you so much.

22. anonymous

we can call the price of the topping $$y$$ and the price of the large plain pizza $$x$$ so the price of the medium plain pizza is $$0.8x$$

23. anonymous

Okay

24. anonymous

then the first part tells you $x+2y=14$ and the second part say $.8x+y=10$

25. anonymous

Right

26. anonymous

now before we solve this, i can make a good guess, which is that $$x=10$$ and $$y=2$$

27. anonymous

because $$10+2\times 2=14$$ and $$0.8x\times 10+2=8+2=10$$

28. anonymous

i am assuming of course that the toppings for the large and small pizza are the same if they are not the same you cannot solve the problem

29. anonymous

Yeah

30. anonymous

in any case to solve $x+2y=14$$.8x+y=10$ multiply the second equation by -2 and add you get $x+2y=14$ $-1.6x-2y=-20$ $-.6x=-6$ $x=-6\div -.6=60\div 6=10$

31. anonymous

so it is right large pizza is $10, medium is$8, toppings are $2 32. anonymous so far so good? 33. anonymous Thank you so much! You make the problems seem so much easier. I might actually get some sleep tonight for school tomorrow! 34. anonymous yw any more or are you done? 35. anonymous I have one more. 36. anonymous It's the hardest one 37. anonymous k 38. anonymous ready? 39. anonymous Nathan wants to go to a hockey game with friends. Tickets are$18, but students can get discounted tickets for $12. They want to spend no more than$80, including $8 for parking. The vehicle they will take can only hold 7 people. Write and graph (it's a regualr coordinate graph) a system of foir inequalities modeling their possible ticket purchases. Let x= number of student tickets and y= number of regular tickets 40. anonymous one thing we know is that $$x+y\leq 7$$ 41. anonymous because at most 7 people can go 42. anonymous we also know that they are going to pay$8 for parking, leaving $$80-8=\72$$ for tickets and so $$12x+18y\leq 72$$

43. anonymous

i think the other two inequalities are the easy ones, both $$x\geq 0$$ and $$y\geq 0$$ which just means you are in quadrant 1

44. anonymous

can you graph $$x+y=7$$?

45. anonymous

Uh, no :/

46. anonymous

|dw:1363921714846:dw|

47. anonymous

if $$x=0$$ you get $$y=7$$ so $$(0,7)$$ is on the graph, and similarly $$(7,0)$$ is on the graph plot the points, connect the dots

48. anonymous

you got it from the picture?

49. anonymous

I can't see your drawing because I'm on my phone, I can't access a computer.

50. anonymous

I know how to graph points, so I should be fine

51. anonymous

ooh ok

52. anonymous

Whatt do I do next?

53. anonymous

the line $$12x+18y=72$$ contains the points $$(0,4)$$ and $$(6,0)$$ so plot those points as well and connect the dots

54. anonymous

55. anonymous

i obviously cannot draw it here for you to see, but that is what you have to do

56. anonymous

Yes, I understand

57. anonymous

then i guess you are done any point that is shaded in the picture is possible

58. anonymous

Ok, sweet. Thank you very much for all your time and help. Have a nice night! :)

59. anonymous

you too