How do you win level 17 on cool math construction fall?

Answer 1

Aim the yellow ball at the right side of the board that is holding the SMALL wheel (the wheel should fall onto the board below it and then onto the one below that) the bottom board will then pivot and hit the red ball. After the red ball moves aim it at the board that is holding the BIG wheel and hit it. The big wheel should then fall and the actions should knock down the "building".