Question

George and Amal can mow their yard together with two lawn mowers in 20min. When George works alone, it takes him 30 min. How long would it take Amal to mow the lawn working alone?

Answer 1

1/g + 1/a = 1/20

1/30 + 1/a = 1/20

1/a = 1/60

a = 60 minutes

Amal can mow the lawn in 60 minutes working alone.