A fish weighs 10kg plus half its weight. How much does it weigh?

Question

The sum of a mother, her baby and her dog’s weight is 170 Kg. How much does the baby weigh if the mother weighs 100 kg more than the combined weight of the baby and the dog, and the dog weighs 60 per cent less than the baby?

Answer 1

Let fish's weight be W:
W = 10 + W/2
W = 20Kg.