Răspuns:
a.
10x-7y=-18 I×4
-4x+5y=16 I×10
__________
40x-28y=-72
-40x+50y=160
____________
/ 22y=88=>y=88:22=>y=4
10x-7×4=-18
10x=-18+28
x=10:10=>x=1
b.
5x-4y=-23 I×3
7x+6y=-9 I×2
__________
15x-12y=-69
14x+12y=-18
____________
29x / = -87=>x=-87:29=>x= -3
5×(-3)-4y=-23
-4y=-23+15
y=8:4=>y=2
