Let the total game played be x
The first game he played he lost 4 points
Mathematically,
Total game = lost game + gained game
x = 4 + gained game
gained game = x - 4
next game he lost 9 points again
out of the total x game he had already lost 4 and now losing 9 points
The remaining game after losing 4 will be x-4
x - 4 = lost game
the new lost game is 9 points
x - 4 = 9
isolating x
you have x = 9+4
x = 13
