Kacie
middle(6-9)
student

Ellen can mow a lawn in 2 hours. Mary can mow the same lawn in 1.5 hours. How long would it take them to mow the lawn together?

Thank- you.

To compare Ellen and Mary it would be helpful to see how many lawns they can mow in the same number of hours. Since 6 is a multiple of 2 and 6 is a multiple on 1.5 I decided to see how many lawns each could mow in 6 hours.

• Ellen can mow one lawn in 2 hours and hence 3 lawns in 6 hours.
   
  
• Mary can mow one lawn in 1.5 hours and hence 4 lawns in 6 hours.

Thus together they could mow 2 + 4 = 7 lawns in 6 hours. That is, together they mow at the rate of 7 lawns in 6 hours or hours per lawn.