Răspuns :
p+s=5
c+s=7
p+c=6
p+s+c+s+p+c=5+7+6
2(p+s+c)=18
p+s+c=9
p=9-7=2 lei pixul
s=9-6=3 lei stiloul
c=9-5=4 lei caietul
c+s=7
p+c=6
p+s+c+s+p+c=5+7+6
2(p+s+c)=18
p+s+c=9
p=9-7=2 lei pixul
s=9-6=3 lei stiloul
c=9-5=4 lei caietul
p+s=5 +
c+s=7
p+c=6
--------------
2p+2s+2c=18 /:2
p+s+c=9
p+s=5=>c=9-5=4lei
c+s=7=>p=9-7=2lei
p+c=6=>s=9-6=3lei
c+s=7
p+c=6
--------------
2p+2s+2c=18 /:2
p+s+c=9
p+s=5=>c=9-5=4lei
c+s=7=>p=9-7=2lei
p+c=6=>s=9-6=3lei