Question

Doua pixuri si cinci DVD-uri costa 11 lei,iar cinci pixuri si doua DVD-uri costa 17 lei.Cat plateste un copil care doreste un obiect din fiecare?

Answer 1

2p+5d=11=>p=(11-5d)/2

5p+2d=17<=>5(11-5d)/2+2d=17 |*2<=>55-25d+4d=34<=>21d=21=>d=1=>un DVD costa 1 leu

p=(11-5d)/2=(11-5)/2=6/2=3lei costa un pix