1. Notam a-nr de porumbei
b-nr de iepuri
2a-nr picioarelor fiacarui porumbel
4a- nr picioarelor fiecarui iepure
{a+b=51 | *(-2) <=> {-2a-2b=-102 <=> {-2b=-102
{2a+4b=132 {2a+4b=132 {4b=132
=>2b=30
b=30:2
b=15(iepuri)
a+15=51
a=51-15
a=36(porumbei)