Se stie:
a + 10 = b
c = a + b = a + a + 10 = 2a + 10
a + 6 = d
e = 2d = 2(a + 6) = 2a + 12
a + b + c + d + e = 80
Inlocuind:
a + a + 10 + 2a + 10 + a + 6 + 2a + 12 = 80
7a = 80 - 38
7a = 42
a = 42 : 7
a = 6
b = 6 + 10 = 16
c = 12 + 10 = 22
d = 6 + 6 = 12
e = 12 + 12 = 24