SOLUTION: Benny and Melanie were able to clean the basement in 4 hours together. It takes Melanie 10 hours to finish this job alone. Without help, how long would it take Benny to finish this

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Benny and Melanie were able to clean the basement in 4 hours together. It takes Melanie 10 hours to finish this job alone. Without help, how long would it take Benny to finish this      Log On


   

Question 950992: Benny and Melanie were able to clean the basement in 4 hours together. It takes Melanie 10 hours to finish this job alone. Without help, how long would it take Benny to finish this job?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Melanie's rate:
( 1 basement cleaned ) / ( 10 hrs )
Let Benny's rate =
( 1 basement cleaned ) / ( t hrs )
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Add their rates of working to get
their rate working together
+1%2F10+%2B+1%2Ft+=+1%2F4+
Multiply both sides by +20t+
+2t+%2B+20+=+5t+
+3t+=+20+
+t+=+6.667+ hrs
+.667%2A60+=+40+
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Working alone, Benny takes 6 hrs 40 min