Question

A red candle is 8 inches tall and burns at a rate of 7/10 inch per hour. a blue cans is 6 inches tall and burns at a rate of 1/5 inch per hour. after how many hours will both candles be the same height
(I just need the equation please)

Answer 1

Let t = number of hours

The first candle starts at 8 inches.
It burns at 7/10 inch per hour, so in t hours it burns (7/10)t inches.
After t hours, its length is 8 - (7/10)t

The second candle starts at 6 inches.
It burns at 1/5 inch per hour, so in t hours it burns (1/5)t inches.
After t hours, its length is 6 - (1/5)t

You want the lengths to be equal, so the equation is

8 - (7/10)t = 6 - (1/5)t