cara mengerjakan soal nomor 15 dan 16 beserta caranya

15. f(x) = 1/2 x (a)

16. -3p + q = -23
4p + q = 19. (-)
-7p = -42
p = -42/-7 = 6

-3(6) + q = -23
-18 + q = -23
q = -23+18
q = -5

maka f(2) = 6(2) + (-5)
12 - 5 = 7 (d)