Răspuns:
Explicație pas cu pas:
{x,y} i.p. cu {3,7} daca
x*3=y*7=k
x*3=k, deci x=k/3
y*7=k, deci y=k/7
4x-3y=252 inlocuiesc x si y
4k/3-3k/7=252
4*7k/21-3*3k/21=252
(28k-9k)/21=252
19k=252/21
k=252/21*19=252/399=84/133=12/19
deci x=12/19*3=12/57
y=12/19*7=12/133
