How old was Eddy Merckx when he first competed in Tour de France in 1969?

Explanation

The Belgian Eddie Merckx (born 1945) rode his first Tour de France in 1969. He won both the polka dot climbing jersey, the green points jersey and the yellow jersey for the overall win aged only 24. This is an accomplishment no-one has been able to match since. The year after, Merckx 'only' won the polka dot and the yellow jersey, whilst his team-mate Walter Goodefroot won the points jersey. Not surprisingly, Merckx became known as 'the Cannibal'.