Question

Elio makes candles that are 14 cm tall. Each candle burns 8 hours before going out. He is wondering how many hours at 21 cm tall candle will burn. How long will a 21 cm tall candle burn?

Answer 1

The answer is 12 hours. I got it right on my Khan Academy.

Answer 2

I would use ratio.
14:8 divide 2
7:4 times 3
21:12
12 hours before going out.