SOLUTION: Twin brothers, Billy and Bobby, can mow their grandparent's lawn together in 92 minutes. Billy could mow the lawn by himself in 25 minutes less time that it would take Bobby. How l

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Question 900324: Twin brothers, Billy and Bobby, can mow their grandparent's lawn together in 92 minutes. Billy could mow the lawn by himself in 25 minutes less time that it would take Bobby. How long would it take Bobby to mow the lawn by himself?
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
1/w+1/r=1/92
1/(r-25)+1/r=1/92
r/((r-25)*r)+(r-25)/(r*(r-25))=1/92
r+r-25/(r*(r-25))=1/92
(2r-25)/(r^2-25r)=1/92
r = 11.655 reject since w=r-25
r = 197.35 Bobby/Robert
w=r-25
w=172.35 Billy/William
check
1/172.35+1/197.35=1/92
0.0108693= 0.0108696
close enough