Hose A can fill a pool in 4 hours. Hose B can fill the pool in 2 hours. If both hoses are turned on

Hose A can fill a pool in 4 hours. Hose B can fill the pool in 2 hours. If both hoses are turned on at the same time how long will it take to fill the pool?

• Hose A can fill the pool in 1/4 of the pool an hour
• Hose B can fill the pool in 1/2 of the pool an hour

In one hour using combined effort, we have:
1/2 + 1/4 = 3/4 of the pool will be filled.

3/4 of the pool gets filled in 60 minutes. We set up a proportion of proportion filled to time where t is the time to fill the full pool:
3/4/60 = 1/t
3/240 = 1/t

Using our proportion solver, we get:
t = 80 minutes or 1 hour and 20 minutes