I would love to understand how to solve this problem: Jess made 3 different stacks of wooden blocks. The first stack was 7 blocks high, the second stack was 5 block(s) higher than the first, and the final stack was 7 block(s) higher than the second. Jess’ little sister knocked over the entire first tower, in the second tower she left 2 blocks standing, and in the final tower she left 3 blocks standing.  How many blocks in total fell down?
Can you explain?