Sophia washes pots in 30 minutes. Her mother takes 15 minutes to wash them. How much time will it take if they wash them together?

Question

Sophia washes pots in 30 minutes. Her mother takes 15 minutes to wash same amount of them. How much time will it take if they wash those dishes together?

Answer 1

Sophie does $1/30$ of the dishes in $1$ minute while her mother does $1/15$. So in a minute they both together do $3/30 $ of the dishes. Thus they do all the dishes in $10$ minutes.

Answer 2

In $10$ minutes, her mother will have washed two thirds of the dishes and Sophia will have washed one third of the dishes.