How do i factor the polynomial?

Which of the following is a justification used while proving the similarity of triangles lom and mon

Two planes leave an airport at the same time, one flying east, the other flying west. the eastbound plane travels 20 mph slower. they are 1600 mi apart after 2 hr. find the speed of each plane.

How long must $542 be invested at a rate of 7% to earn $303.52 in interest? in a easier way