SOLUTION: Working together, Chip and Dale can clean a stadium in 72 minutes. Chip working alone would take three hours to clean the same section. How long would it take Dale to clean the sec

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Question 1010035: Working together, Chip and Dale can clean a stadium in 72 minutes. Chip working alone would take three hours to clean the same section. How long would it take Dale to clean the section if he was working by himself?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +t+ = Dale's time in hrs
+72%2F60+=+1.2+
------------------
rate working together:
[ 1 stadium ] / [ 1.2 hrs ]
Chip's rate working alone:
[ 1 stadium ] / [ 3 hrs ]
Dale's rate working alone:
[ 1 stadium ] / [ t hrs ]
---------------------
Add their rates of working to get their rate
working together
+1%2F3+%2B+1%2Ft+=+1%2F1.2+
Multiply both sides by +1.2%2A3%2At+
+1.2t+%2B+1.2%2A3+=+3t+
+1.8t+=+3.6+
+t+=+2+
It would take Dale 2 hrs working alone
check:
+1%2F3+%2B+1%2F2+=+1%2F1.2+
+.333+%2B+.5+=+.833+
+.833+=+.833+
OK