tolong pakai cara yaa, soalnya buat un selasa bsk:(

17.
f(x) = 3x+5
f(a) =-7
3a+5=-7
3a=-12
a=-4

18. f(x) = 3x + 9
f(k) = 33
3k+9=33
3k=33-9
3k= 24
k=8

20.
2x - y + 5 = 0
y = mx + c →m= gradien

y = 2x+5
m = 2