a,b,c = numerele
a:4 = b:3 => 3×a= 4× b
a:4 = 2:c => 2×a = 4×c => a = 2×c
a = 2×b-40
2×c = 2×b-40 |:2
c = b-20 =>b-c = 20
a |___|___|___|___|
b |___|___|___|
c |___|___|
b-c = un segment = 20
a = 4×20 = 80
b = 3×20 = 60
c = 2×20 = 40
Verificare:
80:4 = 60:3
20 = 20
60-40 = 20
a = 80
b = 60
c = 40