tolong dong,jangan ngasal (poin nya udh aku banyakin tolong dijawab semua)

a. 4y = 12x - 16
dik : x1 = -18 , y1= 7 , m = 12
jawab : y-y1 = -1 PER m ( x - x1 )
y - 7 = -1/12 ( x -(-18) )
y-7 = -1/12 ( x + 18 )
-6y = -1/12 ( x + 18 )
(Coret -6 dg 12 = -2)
y = -1/-2 (x+18) (coret -2 dg 18 =-9)
y = -x + 9

b. 6x + 5y = 18
x1 = -18 , y1 = 7 , m = 6
y-7 = -1/6 (x+18)
-6y = -1/6 (x+18) (coret -6 dg 6 )
-y = -1 (x+18)
y = -x - 18 bagi -1
y = x + 18

(Maaf kalau salah, dan utk c&d masi blm ngerti)