How many hours did Mary babysit? A. 6 hours B. 4 hours C. 2 hours D. 8 hours

Question

Mike, Mary, and Mimi started a sitting service in their neighborhood and call themselves the "Triple M Sitters." During the first month, Mary worked two hours more than Mimi. Mike worked twice as long as Mimi. Their fee is $3.00 per hour and they earned $54 together during the first two weeks. Write and solve an equation that models the situation. How many hours did Mary babysit?

Answer 1

Let x = the number of hours worked by Mimi, since the other two people's hours are based on the number of hours that Mimi worked. 

 

Mary worked (x + 2) hours

 

Mike worked 2x hours

 

If their fee is $3/hour, and they earned $54 together, then we have the following equation:

 

3x + 3(x + 2) + 3(2x) = 54

 

The above equation expresses the total number of hours times the hourly fee for each of the three people

 

3x + 3x + 6 + 6x = 54

 

12x + 6 = 54

 

12x = 48

 

x = 4

 

Mimi worked 4 hours, so Mary worked 4 + 2 = 6 hours