2. For the simultaneous equation ax+by = a^2 + 2ab - b^2

and bx+ay = a^2 + b^2

I know there should be some kinda shortcut but I can't figure it out

3. ABCD is a parallelogram with coordinates A(2,2), B(1,5,4), C(6,6)

Find the coordinates of point of intersection of the diagonals?