The difference of squares formula is a² - b² = (a + b)(a - b). We want this polynomial to be in the form a² - b². We notice that x² and 49 are perfect squares already which means that we don't need the x term. To get rid of it, its coefficient must be 0 because 0 times anything is 0, thus the x term will be removed and we'll be left with x² - 49 which is a difference of squares.
A line is 180 degrees. I found the degree of the angles in-between 126 and M by subtracting 126 from 180. This means that M is also 126. (Plus the intersecting lines are parallel)
