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