The ratio of efficiencies of A and B is 3 : 5. Working together, they can complete the work in 12 days, then how much time does A alone take to complete the same work.

32 days

Let the total work be 12 x 8 = 96 (i.e. no. of days x efficiency)

Then, using the same formula time taken by A alone = \(\frac{Total\; work}{Efficiency}\)

                                                                            = \(\frac{96}{3}\) = 32 days