plis jawab soal mtk no 14 !!!

Bab Program Linear
Matematika SMA Kelas XI

x - y = - 1
x = y - 1

3x + 2y = 12
3 (y - 1) + 2y = 12
3y - 3 + 2y = 12
5y = 12 + 3
y = 15/5
y = 3

x = 3 + 1
x = 4

(4, 3)

f(x, y) = y - 2x

f(4, 3) = 3 - 2 . 4
          = -5

f(0, 1) = 1 - 2 . 0
           = 1

f(0, 6) = 6 - 2 . 0
          = 6

jawabannya B