Question

Your friend has $100 when he goes to the fair. He spends $10 to enter the fair and $20 on food. Rides at the fair cost $2 per ride. Which function can be used to determine how much money he has left over after x rides?

f(x) = −2x + 70
f(x) = 2x + 70
f(x) = −2x − 70
f(x) = −30x + $100