Question

P can do a job in 15 days .in how many days can p and q together

Answer 1

One day work of P is 1/15.
Let the days taken by q to complete one work be x, then one day work of q will be 1/x.
Let the days be y then one day work will be 1/y.
Therefore,
1/y = 1/15 + 1/x
1 = (1/15 + 1/x)/1/y
y = 1/[(x + 15)/15x]
= 15x / (x + 15) <= Answer.

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