A and B are partners in a business. A contributes \(\frac{3}{7}\) of the capital for 9 months and B received \(\frac{4}{13}\) of the profit. For how long B's money was used?

3 months

                  A                     B             Total

Capital        3                     4         ⇒       7

Time           9                    x

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Profit           9                    4         ⇒       13

 Now, ATQ

\(\frac{3 × 9}{4 × x}\) = \(\frac{9}{4}\)

x = 3 

x = 3 months