Albert and Bob are painting rooms at constant, but different rates

Albert and Bob are painting rooms at constant, but different rates. Albert takes 1 hour longer than Bob to paint n rooms. Working side by side, they can paint a total of 3n/4 rooms in 4/3 hours. How many hours would it take Albert to paint 3n rooms by himself?

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #9339