SOLUTION: I've tried this different ways and cant get the answer!! Mark and Maria manicure a lawn together and it take 5 hrs. It takes Mark 7 hrs. alone. How long does it take Maria a

Algebra ->  Rate-of-work-word-problems -> SOLUTION: I've tried this different ways and cant get the answer!! Mark and Maria manicure a lawn together and it take 5 hrs. It takes Mark 7 hrs. alone. How long does it take Maria a      Log On


   



Question 220089: I've tried this different ways and cant get the answer!!

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?

Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
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