Let's do it step by step:
First we need to understand that moving upwards would be addition to y-coordinates, while moving downwards would be deduction to the y-coordinates.
Moving to rightwards would be addition to x-coordinates and leftwards would be deduction to x-coordinates.
As we moved down by 1 unit and up for 2 units, it means that we are originally upward for one unit and downward by 2 units, which makes downwards for 1 units and would be -1 to the y-coordinates:
(-3,1 -1)
=(-3,0)
Therefore the start would be (-3,0).
Hope it helps!
