Question

A candle is 17 in. tall after burning for 3 hours. After 5 hours, it is 15 in. tall. Write a linear equation to model the relationship between height h of the candle and time t. Predict how tall the candle will be after burning 8 hours.

Answer 1

Let x = time of burn , y = length 
x = 3 , y = 17 
x = 5 , y = 15 
m = (15 - 17)/(5 - 3) = -2/2 = -1 
y - 17 = -1(x - 3) 
y = -x + 20 

at x = 8 => y = 12 in   Hope it Helps :)