SOLUTION: Fran Thompson can wash windows in the lobby at the Days Inn in 3 hours. Jill Franks can wash the same windows in 4.5 hours. How long will it take them working together to wash the

Algebra ->  Rational-functions -> SOLUTION: Fran Thompson can wash windows in the lobby at the Days Inn in 3 hours. Jill Franks can wash the same windows in 4.5 hours. How long will it take them working together to wash the       Log On


   

Question 1099742: Fran Thompson can wash windows in the lobby at the Days Inn in 3 hours. Jill Franks can wash the same windows in 4.5 hours. How long will it take them working together to wash the windows?
Found 2 solutions by josmiceli, Alan3354:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Add their rates of washing to get their rate washing together
Fran's rate:
[ 1 job ] / [ 3 hrs ]
Jill's rate:
[ 1 job ] / [ 4.5 hrs ]
Working together:
[ 1 job ] / [ t hrs ]
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+1%2F3+%2B+1%2F4.5+=+1%2Ft+
+1%2F3+%2B+2%2F9+=+1%2Ft+
Multiply both sides by +9t+
+3t+%2B+2t+=+9+
+5t+=+9+
+t+=+1.8+
+.8%2A60+=+48+
Working together, they can wash the windows
in 1 hr 48 min
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check answer:
+1%2F3+%2B+2%2F9+=+1%2F1.8+
+1%2F3+%2B+2%2F9+=+10%2F18+
+1%2F3+%2B+2%2F9+=+5%2F9+
Multiply both sides by +9+
+3+%2B+2+=+5+
+5+=+5+
OK

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Fran Thompson can wash windows in the lobby at the Days Inn in 3 hours. Jill Franks can wash the same windows in 4.5 hours. How long will it take them working together to wash the windows?
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3*4.5/(3+4.5) = 1.8 hours