Question

(02.04 MC) Your friend has $90 when he goes to the fair. He spends $5 to enter the fair and $15 on food. Rides at the fair cost $1.50 per ride. Which function can be used to determine how much money he has left over after x rides? f(x) = 1.5x + 70 f(x) = −1.5x + 70 f(x) = −1.5x − 70 f(x) = −20x + $90

Answer 1

f(x)= $70 - $1.5*x

Explanation:

You know your friend spends $ 5 to enter the fair and $ 15 for food. So the total you spent is given by:

$5 + $15= $20

Knowing that the trips at the fair cost $ 1.50 per trip, and with x being the number of trips, then the cost after x trips will be:

$1.5*x

So the money spent after x rides can be expressed as:

$20 + $1.5*x

Knowing that your friend has $90 when he goes to the fair, to calculate the amount of money he has left after x rides, the amount taken to the fair and the amount spent is subtracted:

$90 - ($20 + $1.5*x)

$90 -$20 -$1.5*x

$70 - $1.5*x

By calling the function f(x) used to determine the amount of money left after x trips, you can finally express:

f(x)= $70 - $1.5*x