tolong!!! pakai caraa

f (x) = ( x - 3 ) / ( x + 4 ) , f (a) = 8
( a - 3 ) / ( a + 4 ) = 8
a - 3 = 8 ( a + 4 )
a - 3 = 8a + 32
a - 8a = 32 + 3
-7a = 35
a = 35/-7
a = -5