SOLUTION: Working together, Sarah and Heidi can milk the cows in 6 hours. If they work alone, it takes Heidi 9 hours longer than it takes Sarah. How long would it take Heidi to milk the cows

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Working together, Sarah and Heidi can milk the cows in 6 hours. If they work alone, it takes Heidi 9 hours longer than it takes Sarah. How long would it take Heidi to milk the cows      Log On


   

Question 275369: Working together, Sarah and Heidi can milk the cows in 6 hours. If they work alone, it takes Heidi 9 hours longer than it takes Sarah. How long would it take Heidi to milk the cows alone?
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
(6 / h) + [6 / (h - 9)] = 1

6h - 54 + 6h = h^2 - 9h

0 = h^2 - 21h + 54

0 = (h - 18) (h - 3)

h = 18

h = 3 does not work because 9 less than 3 would be negative time ...