The sum of 2 times a number and 4 added to 8 times a number

The line containing the midpoints of the legs of right triangle abc where a(-5,5), b(1, 1), and c(3, 4) are the vertices.

You love to play soccer! you make a shot at the net 8 times during a game! of those 8 attempts, you score twice. what percent of the time did you score?

Find the missing dimension! need asap! tiny square is a =3025 in ²