tolong di bantu ...................

Misalkan :
x + 3 = y
x = y - 3

Maka

(f o g) (x) = x² - 4

f(g(x)) = (x - 3)² - 4

f(x) = x² - 6x + 9 - 4

f(x) = x² - 6x + 5

f(-2) = (-2)² - 6(-2) + 5

f(-2) = 4 + 12 + 5

f(-2) = 21