Answer: 180
Step-by-step explanation:
Let the tons of ice the ship was carrying when it set sail be y.
We are told that one third of the original cargo was lost because it had melted on the voyage and that it arrived in Calcutta with 120 tons remaining of its cargo of ice.
This means that (1 - 1/3 = 2/3) remained which was the 120 tons remaining. This implies that:
2/3 × y = 120
2y/3 = 120
2y = 120 × 3
2y = 360
y = 360/2
y = 180
The ship was carrying 180 tons of ice when it set sail
