How do you do this question its on my homework and i dont know how to do it?

Question

Left on together, the cold and hot water faucets of a certain bathtub take 4

 minutes to fill the tub. If it takes the cold water faucet 14

 minutes to fill the tub by itself, how long will it take the hot water faucet to fill the tub on its own?

Answer 1

1/14 + 1/h = 1/4

1/h = 1/4 - 1/14 = 7/28 - 2/28 = 5/28

5h = 28

h = 28/5 = 5.6 minutes to fill with the hot faucet alone