SOLUTION: Bill can mow a lawn in 4 hours, while John can do the same job in 6 hours. how long will it take them to mow the lawn together?

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Bill can mow a lawn in 4 hours, while John can do the same job in 6 hours. how long will it take them to mow the lawn together?      Log On


   

Question 579260: Bill can mow a lawn in 4 hours, while John can do the same job in 6 hours. how long will it take them to mow the lawn together?
Found 2 solutions by nerdybill, josmiceli:
Answer by nerdybill(7384) About Me  (Show Source):
You can put this solution on YOUR website!
Bill can mow a lawn in 4 hours, while John can do the same job in 6 hours. how long will it take them to mow the lawn together?
.
Let x = time (hours) it takes for both
then
x(1/4 + 1/6) = 1
multiplying both sides by 12:
x(3 + 2) = 12
x(5) = 12
x = 12/5
x = 2.4 hours

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Add their rates of mowing
Bill's rate: ( 1 lawn ) / ( 4 hrs )
John's rate: ( 1 lawn ) / 6 hrs )
Let their rate working together = ( 1 lawn ) / ( t hrs )
+1%2F4+%2B+1%2F6+=+1%2Ft+
Multiply both sides by +12t+
+3t+%2B+2t+=+12+
+5t+=+12+
+t+=+2.4+
+.4%2A60+=+24+
It will take them 2 hrs and 24 min working together