Metode eliminasi ,, tolong Yaa

1. x+2y = 7
x+y = 4
dikurang y = 3

2. 3x + 8y = 40
5x- 8y = 16
ditambah = 8x = 56 x = 7

3. 4a + 2b = 12
4a - 3b =3
dikurang = 5b = 15 b = 3