Notam:
s = suma initiala
Metoda algebrica :
3 × s = s : 2 + 50 |×2
6 × s = s + 100
6 × s - s = 100
5 × s = 100
s = 100 : 5
s = 20 lei
Metoda grafica:
3 × s /----/----/----/----/----/----/
s : 2 /----/
6 segmente egale - 1 segment egal = 5 segmente egale = 50
50 : 5 = 10 (valoarea unui segment egal)
3 × s = 6 × 10 = 60
s : 2 = 10
s = 10 × 2 = 20 lei
verificam:
3 × 20 = 20 : 2 + 50
60 = 10 + 50
60 = 60
