HOW DO YOU SOLVE THIS MATH WORD PROBLEM?

let t - time of combined work of Bob and Ken.

1/4 + 1/6 = 1/t

5/12 = 1/t

5t = 12

 t = 2.4  hours. or 2 hours and 24 minutes ..... Answer//

Bob and Ken are painting a room. 

If Bob paints the room alone, 

he can finish the job in 4 hours. 

If Ken paints it alone, he can finish the job in 6 hours. 

How long will it take them to paint it together? 

1/x = 1/4 + 1/6 = 5/12, x = 2.4

The answer is 2 hours and 24 minutes.