bagaimana cara mengerjakan soal ini?beserta jawaban nya

Bab Fungsi
Matematika SMP Kelas VIII

f(x) = px + q

f(-1) = -p + q = -8
f(3) = 3p + q = 12
         ----------------- -
-4p = -20
p = -20 : -4
p = 5

-p + q = -8
-5 + q = -8
q = -8 + 5
q = -3

f(x) = 5x - 3
f(-3) = 5 . (-3) - 3
f(-3) = -15 - 3
f(-3) = -18

jawabannya B

f(-1) = -p + q = -8
f(3) = 3p + q = 12
----------------- - ( dikurang)
-4p = -20
p = -20 : -4
p = 5

-p + q = -8
-5 + q = -8
q = -8 + 5
q = -3

f(x) = 5x - 3
f(-3) = 5 . (-3) - 3
f(-3) = -15 - 3
f(-3) = -18 ( -18 )

Jadi f(-3) adalah -18

Kalau boleh jadikan jawaban terbaik yah.