SOLUTION: Barney can build a barn in 15 hours. david can build a barn in 10 hours. How long will it take for the barn to be built if they work together?

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Barney can build a barn in 15 hours. david can build a barn in 10 hours. How long will it take for the barn to be built if they work together?      Log On


   

Question 301609: Barney can build a barn in 15 hours. david can build a barn in 10 hours. How long will it take for the barn to be built if they work together?
Found 2 solutions by nerdybill, richwmiller:
Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
Barney can build a barn in 15 hours. david can build a barn in 10 hours. How long will it take for the barn to be built if they work together?
.
Barney's rate: 1/15
David's rate: 1/10
.
Let t = time it takes for both
then
t(1/15 + 1/10) = 1
Multiply both sides by 150:
t(10 + 15) = 150
25t = 150
t = 6 hours

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
x/10+x/15=1
multiply by 30 not 150
3x+2x=30
5x=30
x=6
together they can do it in 6 hours