Question 44227
y=7x+14
y=3x-6

then you can write


7x+14=3x-6
4x=-20
x=-5


y=3x-6
y=-15-6
y=-21


the second question


  4x+y = -11
  2x-y =  -1
+____________
  6x   =  -12

x=-2


if x is -2


2x-y=-1
-4-y=-1
y=-3