Ma =(a+b+c+d) : 4 = 16,5
a+b+c+d = 16,5×4 = 66
Ma = (a+b) : 2 = 7,5
a+b = 7,5×2 = 15
c = d:2 ==> d = 2c
a = b + 3
b+3+b = 15
2b = 15-3
2b = 12 /:2
b = 6
a = 6+3 = 9
a+b+c+d = 66
c+d = 66-(9+6) = 66-15 = 51
c+2c = 51
3c = 51 /:3
c = 17
d = 2×17 = 34
a = 9
b = 6
c = 17
d = 34
verificare:
9+6+17+34 = 66