Question

Intr-o parcare sunt 163 de masini albe(a),negre(n), si rosii(r). Daca a+ n=140, iar n+ r=77, cate sunt din fiecare fel?

Answer 1

a+n+r=163
a+n=140
r=163-140
r=23 masini rosii
n+r=77
a=163-77
a=86 masini albe
86+n=140
n=140-86
n=54 masini negre

verificare 54+86+23163 masini

Answer 2

a+n+r=163
stim ca:a+n=140 inlocuim in prima relatie⇒
140+r=163
r=163-140
r=23(marini rosii)
stim ca:n+r=77 inlocuim in prima relatie⇒
a+77=163
a=163-77
a=86(masini albe) inlocuim ce am aflat in prima relatie⇒
86+n+23=163
n=163-109
n=54(masini  negre)
Proba:23+86+54=163