SOLUTION: Working alone, Shawna can clean an attic in 13.3 hours. Cody can clean the same attic in 12.3 hours. If they worked together how long would it take them?

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Question 946331: Working alone, Shawna can clean an attic in 13.3 hours. Cody can clean the same attic in 12.3 hours. If they worked together how long would it take them?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Shawna's rate of cleaning:
( 1 attic ) / ( 13.3 hrs )
Cody's rate of cleaning:
( 1 attic ) / ( 12.3 hrs )
Cleaning together:
( 1 attic ) / ( t hrs )
--------------------
Add their rates to get rate
cleaning together
+1%2F13.3+%2B+1%2F12.3+=+1%2Ft+
Multiply both sides by
+13.3%2A12.3%2At+
+12.3t+%2B+13.3t+=+12.3%2A13.3+
+25.6t+=+163.59+
+t+=+6.3902+
+.3902%2A60+=+23.414+
+.414%2A60+=+24.843+
---------------------
Working together, it takes them
6 hrs 23 min 25 sec
-------------------
check:
+1%2F13.3+%2B+1%2F12.3+=+1%2F6.3902+
+.07519+%2B+.0813+=+.15649+
+.15649+=+.15649+
OK