SOLUTION: Trisha can mow a certain lawn in 40 minutes. Joe can mow the same lawn in 15 minutes. How long will it take them (to the nearest minute) to mow the lawn if they work together.?

Algebra ->  Human-and-algebraic-language -> SOLUTION: Trisha can mow a certain lawn in 40 minutes. Joe can mow the same lawn in 15 minutes. How long will it take them (to the nearest minute) to mow the lawn if they work together.?      Log On


   

Question 888578: Trisha can mow a certain lawn in 40 minutes. Joe can mow the same lawn in 15 minutes. How long will it take them (to the nearest minute) to mow the lawn if they work together.?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Trisha's rate:
( 1 lawn / 40 min )
Joe's rate:
( 1 lawn / 15 min )
Add their rates of mowing to get
their rate mowing together
Let +t+ = time in minutes to mow
lawn
+1%2F40+%2B+1%2F15+=+1%2Ft+
Multiply both sides by +120t+
+3t+%2B+8t+=+120+
+11t+=+120+
+t+=+10.91+
Working together, it will take them 11 minutes