write a formula

Question

A candle is lit and the length of the burning candle changes at a constant rate of -1.6 inches per hour. 3 hours after the candle was lit the candle was 8.9 inches long.

Write a formula that expresses the remaining length of the candle in inches, , in terms of the number of hours  that have elapsed since the candle was lit.

Answer 1

4.8 inches have burned (3 x 1.6)

Starting size of the candle was 13.7 (4.8 + 8.9)

L = 13.7 - 1.5t