Fie numerele a,b,c,d
a+b+c+d=8x9+10
a+b+c+d=82
n=numărul care se scade din toate numerele
(a-n)+(b-n)+(c-n)+(d-n)=10+20+15+5
(a-n)+(b-n)+(c-n)+(d-n)=50
82-50=32
N=32:4
N=8
A=20+8. A=28
B=10+8. B=18
C=15+8. C=23
D=5+8. D=13
Verificare:28+18+23+13=82
Raspuns:a=28
b=18
c=23
d=13