Question

6 pixuri....8 caiete...52lei
4 pixuri...10 caiete...58 lei
1 pi=?lei
1 caiet=lei?

Answer 1

Fie 
pixuri=p;
caiete=c;
6p+8c=52x(-1)(inmultim relatia cu minus 1)
4p+10c=58(a)(relatia a-sa nu se faca confuzie,da?)
<=>
-6p-8c=-52
4p+10c=58
<=>
-2p+2c=6
2(-p+c)=6
<=>
2(c-p)=6
c-p=3
c=3+p;(b)
=>a+b 
4p+10c=58
4p+10(3+p)=58
4p+30+10p=58
14p=58-30
14p=28
p=2 lei;
c=3+p;
c=3+2;
c=5 lei;