3x+y=2
4x+y=20
what is the answer?

{ 3 x + y = 2   * ( -1 )
   4 x + y = 20   

-3 x - y  = - 2
 4 x + y = 20

 x  = 18

For y :

4 x + y = 20

4*18 + y = 20

72 + y = 20

y = 20 - 72

y = -52

hope this helps!.

One way is to make the first equation negative and add it to the first equation so
-(3x+y=2)
-3x-y=-2
add to 4x+y=20
4x+y=20
-3x-y=-2+
1x+0y=18
x=18
subsitue
3x+y=2
3(18)+y=2
54+y=2
sutract 54 from both sides
y=-52

x=18
y=-52
solution in point form or (x,y) form is
(18,-52)