Mary can clean the house in 6 hours. Her younger sister Ruth can do the same job in 9 hours. In how many hours can they do the job if they work together?

Respuesta :

This question has the same concept as the one I answered earlier, together, Ruth and Mary need 4 and 1/2 hours to clean the house.

**and if it isnt too much trouble can you please mark brainliest for both these answers.