help? 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) = -16x + $80
f(x) = -1.25x + 64
f(x) = -1.25x - 64

Question

help? 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) = -16x + $80
	f(x) = -1.25x + 64
	f(x) = -1.25x - 64

anonymous · Answer

it cost 1.25 dollars per ride, and each ride will subtract the total amount of money, so -1.25x. He spent 16 dollars on food and entry fee, so he has 64 dollars left.
So the amount of money you have left equals to the amount of money you spent from the 64 dollars.
so y=-1.25x+64
(the negative in front of 1.25 indicate that he is spending the money)
ANSWER : C