<PRE><B>Question 758019</B>
Tina can completely weed her vegetable garden in 1hr and 30 min.
 Her friend marisa can do the same in 2 hrs.
 if they worked together, how long would it take? 
:
Let t = the time required when working together (in hrs)
Let the completed job = 1
:
Each will do a fraction of the job, the two fractions add up to 1
:
{{{t/1.5}}} + {{{t/2}}} = 1
multiply by 6 to get rid of the denominators, results
4t + 3t = 6
7t = 6
t = 6/7 hrs, or converted to minutes: 6/7 * 60 = 51.4 minutes
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