15. Diketahui f(x) = ax + b, f(-8) = 11, dan f(7) = -19. nilai f(10) adalah... A. -2 B. -5 C.-25 D.-30

f(x) = ax+b
f(-8) = a(-8)+b
11 = -8a+b .....1
f(7) = a(7)+b
-19 = 7a+b ......2

 11 = -8a+b
-19 =  7a+b  -
30 = -15a
30/-15 = a
-2 = a

subtitusi a = -2
11 = -8a+b
11 = -8(-2)+b
11 = 16+b
11-16 = b
-5 = b

f(x) = ax+b
f(10) = -2(10)+(-5)
= -20-5
= -25

Jawabannya (C)