Diketahui sistem persamaan berikut. 2x + 3y = 15 2y + 3x = 45 Nilai dari x - y adalah..

> 2x + 3y = 15
2y + 3x = 45
> 2x + 3y = 15 (× 3 )
3x + 2y = 45 (× 2 )
> 6x + 9y = 45
6x + 4y = 90
= 5y = -45
y = -9
> 2x + 3(-9) = 15
2x + (-27) = 15
2x = 15 + 27
2x = 42
x = 21