Question 272395
With word problems like these, you have to take into consideration that there is one job that will be done in a specific period of time.
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Tom can do 1 job (the whole job) in 45 minutes.  So he can do 60/45 jobs per hr.  Maria can do 60/65 jobs per hour.
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Working together, they can do:

60/45x + 60/65x = 1
(4/3 + 12/13)x = 1
(1.33333 + .92037)x = 1
2.25370x = 1
x = 1/2.2537 = .44371
x =  .44371 hr = 26.6226 min
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You can check to see if their combined work will complete in 26.6226 min.
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26.6226/45 =  .591 of a job
26.6226/65 =  .409 of a job
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Pretty close...