4x - (x + y) = 28
4x + (-x -y) = 28
4x - x - y = 28
3x - y = 28 ... (2)

Persamaan (1) dan (2) :

2x - 5y = 10
3x - y = 28

= 2x - 5y = 10
15x - 5y = 140
________________ -
- 13 x = -130
x = 10

(1) 2x - 5y = 10
2 x 10 - 5y = 10
20 - 5y = 10

20 - 10 = 5y
10 = 5y
2 = y

Penyelesaian, x = 10 dan y = 2

(2) { 0,19x - 1,05y = 2
{ 3,8x + 8,5y = 10,2

Jawaban :

Persamaan (1)

0,19x - 1,05y = 2
0,19x x 100 - 1,05y x 100 = 2 x 100
19x - 105y = 200 ... (1)

Persamaan (2)

3,8x + 8,5y = 10,5
3,8x x 10 + 8,5y x 10 = 10,5 x 10
38x + 85y = 105 ... (2)

19x - 105y = 200
38x + 85y = 105

38x - 210y = 400
38x + 85y = 105
_________________ -
- 295y = 295
y = -1