Find the !
ik
x1= 5 y1= 3
x2= 1 y2= 1
5-3 / 1-1
would the answer be -3 or 3?

Actually, the slope is undefined. this is because x remains the same as y increases. as a graph this looks like x=1, a straight vertical line at 1x. this can not be expressed as a slope, so we write undefined. 

You arrange them wrong
X1=1, Y1=3
X2=1, Y2=5
(X1, Y1)
(X2, Y2)

How you did it kinda confused me a bit

I’m going to infer you said parallel.solve for yy= -1/2x+7/4lines that are parallel have the same slope, different y intercept.so we know m is -1/2then from there solve for y intercept.