Question 220089
Mark and Maria manicure a lawn together and it take 5 hrs. It takes Mark 7 hrs. alone. How long does it take Maria alone?
.
Let x = time it takes for Maria do it alone
then
5(1/7 + 1/x) = 1
Multiply both sides by 7x:
5(x + 7) = 7x
5x + 35 = 7x
35 = 2x
17.5 hours = x