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Ina si Ana au impreuna 125 timbre .Ina are cu 5 timbre mai mult decat dublul nr timbrelor Anei.Cate timbre are Ina? .b) Cate timbre are Ana?C) cate timbre trebuie sa-i dea Ana colegei sale ina casa aiba o patrime din nr timbrelor Inei?

Răspuns :

x-nr de timbre are Ana
y-nr de timbre are Ina
x+y=125 timbre
y=2*x+5
x+2x+5=125
3x=125-5
x=120:3
x=40
a)ina are 125-40=85 timbre
b)Ana are 40 de timbre
c)40-x=1/4*85+x
4*(40-x)=85+x
160-4x=85-x
160-85=x+4x
5X=75
x=15