Tolong di jawab ya kk bang please

13. harga buku Rp.450,- (C)

10. Baju → x & celana → y
3x + 2y = 235.000 → ×2
2x + y = 140.000 → ×3
_________________
6x + 4y = 470.000
6x + 3y = 420.000
_________________ -
y = 50.000
2x + y = 140.000
2x + 50.000 = 140.000
2x = 140.000 - 50.000
2x = 90.000
x = 90.000/2
x = 45.000
Maka, 4x + 5y = (4×45.000) + (5×50.000)
= 180.000 + 250.000 = 430.000 (B)

11. x - y = 5 x - y = 5
x + 2y = -1 x - (-2) = 5
_________ - x = 5 - 2
-3y = 6 x = 3
y = 6 / -3 Maka, himpunan {x,y} ↓↓
y = -2 → {3,-2} (A)

13. Buku → x & pensil → y
2x + 4y = 1.400 → ×2
3x + 2y = 1.600 → ×4
______________
4x + 8y = 2.800
12x + 8y = 6.800
______________ -
-8x = -4.000
x = -4000/-8
x = 500 (B)