a/2 ( bunica )
1/3 ( a - a/2 ) = 1/3 x a/2 = a/6 ( fiica )
2/3 ( a - a/2 - a/6 ) = 2/3 ( 6a/6 - 3a/6 - a/6 ) = 2/3 x 2a/6 = 2a/9
a - a/2 - a/6 - 2a/9 = 10
18a - 9a - 3a - 4a = 180
2a = 180
a = 90 ( capsuni )
Proba: 90/2 = 45 ( bunica )
1/3 ( 90 - 45 ) = 1/3 x 45 = 15 ( fiica )
2/3 ( 90 - 45 - 15 ) = 2/3 x 30 = 20 ( gemenii )
45 + 15 + 20 + 10 = 90