Question

The unit price (rate) per 1 gallon of gas is $3.00. The constant of proportionality is $3.00. Using the unit rate, how much will 15 gallons of gas cost?

a) $3.00
b) $21.00
c) $45.00
d) $90.00

Answer 1

Hi I’m pretty sure the answer is c.

Since 1 gallon is $3 you know that if you multiply 1 by 15 and ALSO multiply $3 by 15 you will have your answer.

15x1 gallon = 15 gallons
15x$3 = $45

15 gallons = $45