It would be 31+t.
Unless there's more to this question.
So here's how to do it,
slope intercept form is y=mx+b
m is the slope, b is the y- intercept, X is your unknown variable.
you need to solve to get y by its self to get your slope.
for perpendicular lines flip the slope
ex 1, smy=2x+6 --- slope of a perpendicular line will be 1/2
ex 2, y=3/2+8 ---8 perpendicular lien would have a slope of 2/3
parallel lines have the same slope so any equation with with the same slope will be parallel if it has the same degree.
ex. y=2x+14 is parallel to y= 2x+56
slope can be found using the following formula if you have two sets of points on the same line
m= y2-y1 ÷ X2 - X1
If you mean (3n-2m)^2 then the answer is
9n^2-12mn+4m^2
So B