Răspuns:
Gina = 30 narcise
Nadea = 50 narcise
Petra = 90 narcise
Explicație pas cu pas:
N = G + 20
G = P/3 => P = 3G
P = N + 40 => N = P - 40 = 3G - 40
G + 20 = 3G - 40
20 + 40 = 3G - G
60 = 2G
G = 60 : 2
G = 30
N = 30 + 20 = 50
P = 3 x 30 = 90
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