A = vase de 12 l
B = vase de 16l
C = vase de 25 l
12A + 16B + 25C = 697
A + B + C = 45
A = 3B - 4
12(3B - 4) + 16B + 25C = 697
3B-4 + B + C = 45
36B - 48 + 16B + 25C = 697
4B + C = 49
52B + 25C = 745
C = 49 - 4B
52B + 25(49 - 4B) = 745
52B + 1225 - 100B = 745
1225 - 745 = 100B - 52B
480 = 48B
B = 10
C = 49 - 4x10 = 49-40 = 9
A = 45 - 10 - 9 = 26