Answer: The weight of first melon = 16 kg.
The weight of second melon = 12 kg
The weight of third melon = 4 kg
Explanation:
Since we have given that
Weight of melon one = 16 kg
According to question, we have given that Melon 1 is 4 times heavier than melon 3.
so, Weight of melon 3 is given by

According to question, Melon 1 and melon 2 together are 7 times heavier than melon three.
So, it becomes

Hence, the weight of first melon = 16 kg.
The weight of second melon = 12 kg
The weight of third melon = 4 kg.