Answer:
line 2 and line 3
Step-by-step explanation:
line1=y=-9x+6. gradient 1= -9
line2=x+⅓y=-6
⅓y=-6-x. gradient2= -3
y=-18-3x
line3=y=-3x-8. gradient3= -3
line4=y+7=-1/9x-4/9
y=-1/9x-4/9-7. gradient4= -1/9
y=-1/9x-7⁴/9
parallel lines have the same gradient
