Answer:There are two right triangles. You need to find the opposite side (the height) of each of them. The difference between the two is the height of the blade, x.
You know the adjacent, 440, and you are looking for the opposite, so you need to use tan for both.
The first reaction represented is a decomposition reaction due to the fact the bonded pair are being split apart.
The second equation is a single displacement because the B and C have switched places, which is the only change making it a single displacement. If there had been another bond and A had also moved, it would be double.