a+b = 27
b = a-13 => a = b+13
a |____|+13
b |____|
avem 2 segmente egale +13 = 27
27 - 13 = 14
14 : 2 = 7 ( un segment)
a = 7+13 = 20
b = 7
Verificare:
20+7 = 27
metoda algebrica
a+b = 27
b = a-13
inlocuim pe b in prima ecuatie
a + a-13 = 27
2×a = 27+13
2×a = 40
a = 40:2
a = 20
b = 27-20 = 7
a = 20
b = 7