Writing and solving algebraic equations

Question

Need help writing the equation for this word problem:

There are two leaking pipes. A bucket is put under each leak. The two buckets each hold the same amount of water. The bucket under the first leak fills in 20 minutes. The bucket under the second leak fills in 35 minutes. One bucket is removed and the other one is placed under the two leaks. How long will it take for the one bucket to fill completely?

Answer 1

The first leak fills the bucket in 20 mins, so it fills 1/20 of the bucket in one minute.

The second leak fills the bucket in 35 mins, so it fills 1/35 of the bucket in one minute.

the combined speed is 1/20 + 1/35 = 7/140 + 4/140 = 11/140

One bucket will be filled in 140/11 = 12 and 72/99 minutes = 12 and 8/11 minutes

12 minutes and 43.63 seconds