IMO 1971 LL CUB13

Origin: CUB

Problem

One Martian, one Venusian, and one Human reside on Pluton. One day they make the following conversation: Martian : I have spent 1/12 of my life on Pluton. Human : I also have. Venusian : Me too. Martian : But Venusian and I have spend much more time here than you, Human. Human : That is true. However, Venusian and I are of the same age. Venusian : Yes, I have lived 300 Earth years. Martian : Venusian and I have been on Pluton for the past 13 years. It is known that Human and Martian together have lived 104 Earth years. Find the ages of Martian, Venusian, and Human.5