Problema Solution

An elementary school teacher can assemble and staple the weekly newsletter three times faster than her student aide. Working together, they can assemble and staple the letters in 15 minutes. How long would it take each, working alone, to complete the job?

Answer provided by our tutors

Let


x = the time the teacher needs to staple the letters alone, x>0


1/x letters per min is the rate of the teacher


3x = the time the student needs to staple the letters alone


1/(3x) letters per min is the rate of the student


1/15 letters per min is the together rate


1/x + 1/(3x) = 1/15

........


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........

x = 20 min


3x = 3*20 = 60 min = 1 hr


The teacher needs 20 min to complete the job alone.


The student needs 1 hour the complete the job alone.