Răspuns:
Explicație pas cu pas:
Metoda grafica
Dan l-------l-------l
Razvan l-------l } total = 123 timbre
George l-------l-------l + 28
123 - 28 = 95 → suma celor 5 segmente ( parti ) egale
95 : 5 = 19 timbre are Razvan
2 × 19 = 38 timbre are Dan
38 + 28 = 66 timbre are George
_________________________
Verific: 38 + 19 + 66 = 123 timbre au cei trei copii
D + R + G = 123
D = 2 × R
D = G - 28
G = 28 + D
G = 28 + 2 × R
2 × R + R + 28 + 2 × R = 123
5 × R + 28 = 123
5 × R = 123 - 28
5 × R = 95
R = 95 : 5
R = 19
D = 2 × 19
D = 38
G = 28 + 38
G = 66
