a + c = 2b
a,b(c) + b,c(a) +c,a(b) = 13,(3)
a,b(c) = (90a + 10b +c -b)/90 = (90a + 9b +c)/90
b,c(a) = (90b + 10c + a -c)/90 = (90b + 9c +a)/90
c,a(b) = (90c + 10a +b - a)/90 = (90c + 9a +b)/90
100(a+b + c)/90 = 40/3
10(a + b + c) = 120 a + b + c = 12 3b = 12 b = 4
a + c = 8
daca : a = 1 c = 7 1,4(7) + 4,7(1) + 7,1(4) = 133/90 + 424/90 + 643/90 = 1200/90 = 13,(3)
a = 2 b = 4 c = 6
a = 3 b = 4 c = 5
a = 4 b = 4 c = 4