if the points a(-2,-1),b(1,3),c(x,1) and d(1,y) from a parallelogram find x and y

x=4 and y=-3

You konow that diagonals of paralelogram bisect each other. So, using points a and b we got the y- coordinate of the point of intersection using mid point formula and then by applying the mid point formula again we get the x- coordinate of the point of intersection .Then you can easily find out x and y using mid point formula.