gaini +curci +capre +iepurasi =100 capete
2x gaini + 2x curci+4x capre+4x iepurasi=260 picioare
Notam g=gaini; curci=c; capre=a iepuri=i
g +(g+18)+ a+(a+10)=100 capete
2xg +2xa =100-28
2x(g+a)=72
g+a=72:2
g+a=36
2xg+2xc+4xa+4xi=260
2(g+c) +4×(a+i)=260 l (: 2)
g+c+2×(a+i)=130
c+18+c+2×(a+a+10)=130
2×c+2×2a=130-18-2×10
2×(c+2a)=92
c+2a=92:2
c+2a=46
c+2a=46 l (-)
c+a=36
_________
/ a=10 capre
10+10=20 iepurasi
36-10=26 curci
26+18=44 gaini
Verific:
2 x ( 26 + 44) + 4 x ( 10 + 20) = 2 x 70 + 4 x 30=140+120=260 picioare
26+44+10+20=100 capete