Soal Matematika Kelas 8 Tolong bantuin pake cara. Makasih~

9) 3x + 2y = 2 |×2
x - 4y = 10
maka
6x + 4y = 4
x - 4y = 10
-----------------(+)
7x = 14
x = 2
subtitusi ke pers :
x - 4y = 10
2 - 4y = 10
- 4y = 10 - 2
- 4y = 8
y = - 2
nilai x + y = 2 + (-2) = 0 ( A )

10)(x , y ) = ( -3 , 2 )
ax + by = 4 => - 3a + 2b = 4
- 2ax - by = 2 => 6a - 2b = 2
-------------------------------------------(+)
3a = 6
a = 2
subtitusi a = 2 ke pers :
- 3a + 2b = 4
- 3(2) + 2b = 4
- 6 + 2b = 4
2b = 4 + 6
2b = 10
b = 5
nilai a = 2 , b = 5 ( C )