tolong pakai cara ya :-) no. 16

f(x ) = 5x - 4
f(-2) = 5 ( -2 ) - 4 = -10-4 = -14 ( a )
f(b) = 11 ⇒ 5x -4 = 11 , 5x = 15 , x = 3 

a = -14  b = 3 
a + b = -14 + 3 = -11
semoga membantu