tolong dijawab ya no. 21 dan 22 pake caranya ya

21. -6x + (-3)y = 18
-6x - 3y = 18
-2x - y = 6
-y = 2x + 6
y = -2x - 6 <=> f(x) = -2x - 6

22. f(x) = ax + b

f(3) = a(3) + b
3a + b = 3 ..............(1)

f(1) = a(1) + b
a + b = 3 ............... (2)

3a + b = 3
a + b = 3
__________ -
2a = 0
a = 0

a=0, subtitusi ke pers (2)

0 + b = 3
b = 3

jadi, a=0 dan b=3 ( jawabannya ga ada di pilihan gandnya)