Answer:
The y axis
Step-by-step explanation:
Perpendicular means for a line to create a 90 degree angle, like it does on the y axis.
Hope this helps!
x+142 =3x+64
subtract x from each side
142 = 2x+64
subtract 64 from each side
142-64 = 2x
78=2x
divide by 2
78/2 = x
x=39
The number is 39
I think the person on top is right

now, the one below that, which is equivalent to that? well, just look above it