1.Реши систему: x=4 7x−y=11 2. x=9 7x−y=11

Question

1.Реши систему:
x=4
7x−y=11
2.
x=9
7x−y=11

Answer 1

1) 7*4-y=1
28-y=1
-y=1-28
-y= -27
y= 27
2) 7*9-y=11
-y=11-63
y=52