It is a parallelogram!
Also you haven't really put any other info...
Midpiont=(_2+3\2), (4+_1/2)
=2/2,6/2
=1,3
The answer is No, they are not proportional. This is because 8/42 is not equal to 20/105.
It is rational number because irrational numbers are endless
Suppose the line is y=mx+b
when x=3, y=15, so 15=3m+b
when x=-1, y=-13, so -13=-m+b
solve the system of these two equation, you get m=7, b=-6
so the linear equation is y=7x-6