find a and b if the point A(a-1,3) B(2,2a) C(3,b+7) and D(2,1) are vertices of parllelogram

find a and b if the point A(a-1,3) B(2,2a) C(3,b+7) and D(2,1) are ver

1.	find a and b if the point A(a-1,3) B(2,2a) C(3,b+7) and D(2,1) are vertices of parllelogram
Answer» a=2 and b=-5