Let's take the large ships be l, the medium one's be m and small one's be s.
From the information given in the question, we get that
4l = 7s
3m = 2l + 1s
6m = 4l + 2s, so 6m = 9s, so 2m = 3s, m = \(\frac{3s}{2}\) = \(\frac{6l}{7}\)
Total quantity of water in 36 journeys:
t = 36 × [15l + 7m + 14s] = 36 × [15l+6l+8l] = 36 × 29l
t = x [12l+14m+21s], here x = number of journeys
36 × 29l = x[12l + 12l + 12l] = 36l × x
x = 29
So, The total journey will be 29
The correct option is (C)