a: 4 = a:2-10 |×4
a = 2×a - 40
2×a- a = 40
a = 40
Verificare:
40 : 4 = 40 :2 -10
10 = 20-10
10 = 10
sau
a : 2 - a : 4 = 10
a: 4 |____|
a : 2 |____|____|
2 segmente egale - 1 segment egal = 1 segment egal = 10
a : 4 = 10
a = 4×10 = 40
a : 2 = 2×10 = 20
10 = 20-10
