Question 1043165
Not sure what you mean about gradients being the same.
So going from A to O would be the same procedure as going from E to B. 
Similarly, going from O to B would be the same procedure as going from A to E.
So starting with O and going to B, you move 4 units right, 4 units up.
B:(0,0)+(4,4)=(4,4)
So starting with A, move 4 units right, 4 units up to find E.
E:(-2,1)+(4,4)=(2,5)
As a check, going from A to O, move 2 units right, 1 unit down,
O:(-2,1)+(2,-1)=(0,0)
So then moving from E to B should also be the same,
B: (2,5)+(2,-1)=(4,4)
So we're consistent
E: (2,5)