Question

Your friend has $80 when he goes to the fair. He spends $4 to enter the fair and $12 on food. Rides at the fair cost $1.25 per ride. Which function can be used to determine how much money he has left over after x rides?
f(x) = -1.25x - 64
f(x) = -1.25x + 64
f(x) = -16x + $80
f(x) = 1.25x + 64
Any help would be great:) I just can not figure this out!!

Answer 1

the second one

Answer 2

do you need explanation?

Answer 3

Yes please:)

Answer 4

if u still would like an explanation.. here i go :)

your friend initially had $80 but then spent $16. therefore, before going on rides he has $64. This is where the +64 comes from.

now since he will be spending money, the amount will be less each time,, this is why -1.25x is valid where
- means that we are spending
1.25 is the cost per ride
x is the number of times he wishes to go on rides.

therefore, y=-1.25x+64 tells this story the best.
x y
0 64 -> if he doesnt go on any rides he will have $64 in his pocket
1 62.75 -> if he goes on one ride he has $62.75 left
........
5 57.75 -> 5 rides he has even less money.