Burnt Candles

Algebra Level 3

I have 2 candles of the same length but different burning rates: one burnt in 4 hours and the other in 5 hours. Initially lighting at the same time, the lights are on for some time before being put out, and the physical length of one candle 4 times as long as than the physical length of the other.

How long in minutes have the candles been burning for?