How to solve system by elimination method

5x-2y=42
3x+4y=20

2x+4y=48
4x+2y=66

5x-2y=42
3x+4y=20

multiply 2 to the first one

10x - 4y = 84
3x + 4y = 20
---------------------Add
13x = 104
x = 104/13 = 8
Substitute into either equations to find y
x = 8 then y = -1
*************************
2x+4y=48
4x+2y=66
Multiply first with 2

4x + 8y = 96
4x + 2y = 66
--------------------Subtract

6y = 30

y = 5
so
x = 14

1).
5x - 2y = 42
3x + 4y = 20
10x - 4y = 84
13x = 104
x = 8
y = -1

2).
2x + 4y = 48
4x + 2y = 66
8x + 4y = 132
6x = 84
x = 14
y = 5