Diketahui fungsi f(x) =6×-3,g(x) +5x+4 dan (fog)(a)=81.maka nilai a

fog(a)
= f(g(a))

6(5a + 4) - 3 = 81
30a + 24 - 3 = 81
30a + 21 = 81
30a = 81-21
30a = 60
a = 60/30
a = 2