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put this solution on YOUR website!John and Fred must mow the lawn before they can go swimming.
:
By themselves, John would take 30 minutes and Fred would take 45 minutes. How long would it take to mow the lawn with both working together?
:
Let t = time in minutes working together
:
During this time we can say John would do t/30 of the job and
Fred would do t/45 of the job
:
Let the completed job = 1, giving us an easy equation:
:
+
= 1
:
We can get rid of the denominators by mult by 90, then we have:
3t + 2t = 90
:
5t = 90
:
t = 90/5
:
t = 18 min when they work together
:
:
Check our solution:
+
=
+
= 1
