Răspuns:
Explicație pas cu pas:
[tex]\frac{a}{4} +\frac{b}{4} =20\\ \\ \frac{c}{2} +\frac{d}{2} =12\\ \\ \frac{a}{4} =d\\ \\ \frac{b}{4} +2c+8=d\\ \\ \frac{a}{4} +\frac{b}{4} +2c+8=2d\\\\ \\ 20+2c+8=2d\\ c+d=24\\ \\ 2c-2d=-28\\ c+d =24\\\\c-d=-14\\c+d=24\\ \\ 2c=10\\ c=5\\ d=19\\ a=4d=76\\ \\ a+b=80\\ b=4[/tex]
