Answer:
It will take them both 24 minutes to mow the lawn if they are working together.
Explanation:
Given that Sam can mow a lawn in 40 minutes, and Melissa can mow the same lawn in 80 minutes, to determine how long does it take for both Sam and Melissa to mow the lawn if they are working together, the following calculation must be performed:
1/40 + 1/60 = 1 / X
3X + 2X = 120
X = 120/5
X = 24
Thus, it will take them both 24 minutes to mow the lawn if they are working together.