Blocks

Goal and rules of the game:

You are probably familiar with the game Tetris. 'Blocks' is a bit like Tetris.
There are sums falling down and you have to figure out whether they belong left or right of the central line.
The cursor arrows on the keyboard can be used to move the blocks left or right or make them fall down:

Be careful: not all answers go left or right, sometimes the answer to a sum belongs in the center. These are bonus blocks and they will remove one underlying row.