A’B’C’D’ is obtained by translating ABCD 3 units to the right (i.e. a positive translation of 3 units along the x axis) and 5 units down (i.e. a negative translation of 5 units along the y axis).
So, in order to go back to ABCD, we have to invert both translation: we have to go 3 units to the left (i.e. a negative translation of 3 units along the x axis) and 5 units up (i.e. a positive translation of 5 units along the y axis).
