Lisa cleans a house in 1 hour, it takes Mia three times as long; how long will it take working together?

in three hours, working together, they can clean 4 houses. Right?

so rate is 4houses/3hrs, or or one house per 3/4 hr.

Ans: 45min

Thanks so much Bob, really helps

To find out how long it will take Lisa and Mia to clean the house together, we can determine Mia's cleaning rate relative to Lisa's.

Given that Lisa takes 1 hour to clean the house, Mia takes three times as long, which means she takes 1 * 3 = 3 hours.

Now, let's calculate their combined cleaning rate. Lisa can clean the entire house in 1 hour, so her rate is 1/1 = 1 house per hour. Similarly, Mia can clean the entire house in 3 hours, so her rate is 1/3 = 1/3 house per hour.

To find the combined cleaning rate when they work together, we add their individual rates together. So their combined cleaning rate is 1/1 + 1/3 = 4/3 houses per hour.

Finally, to determine how long it will take for them to clean the house together, we take the reciprocal of their combined rate. So it will take them 3/4 hours or 0.75 hours, which is equivalent to 45 minutes.

Hence, it will take Lisa and Mia working together 45 minutes to clean the house.