A clerical worker takes 3 times as long to finish a job as it does an executive secretary

A clerical worker takes 3 times as long to finish a job as it does an executive secretary. Working​ together, it takes them 4 hr to finish the job. How long would it take the clerical​ worker, working​ alone, to finish the​ job?

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/4 = rate together {job/hour}
1/x = executive rate {job/hour}
1/(3x) = clerical rate {job/hour}

​1/x + 1/(3x) = 1/4 {executive rate + clerical rate = together rate}
12 + 4 = 3x {multiplied entire equation by 12x to eliminate fractions}
16 = 3x {combined like terms}
x = 16/3 {divided each side by 3}
3x = 16 {substituted 16/3, in for x, into 3x}

It would take the clerical worker 16 hours, working alone.

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