Metoda algebrica:
Fie a numarul:
2 × a + a : 2 = 510 |×2
4×a + a = 1020
5×a = 1020
a = 1020 : 5
a = 204 (numarul)
Verificare:
2 × 204 + 204 : 2 = 408 + 102 = 510
Metoda grafica:
2×a |_____|_____|_____|_____|
a : 2 |_____|
avem 5 segmente egale = 510
510 : 5 = 102 (un segment egal)
2×a = 4×102 = 408
a :2 = 102
a = 102 × 2 = 204 (numarul)
