Let the required number of days be x. More men, Less days (Indirect proportion) Less hours, More days (Indirect proportion) Men 36 : 30 :: 16 : x Hours/ day 8 : 9 Therefore, \( \Large \left(36 \times 8 \times x\right) = \left(30 \times 9 \times 16\right) \) Therefore, x = \( \Large \frac{30 \times 9 \times 16}{36 \times 8} \) = 15 days