Use multiplication and the distributive property to find the quotient 171 divided by 9

Me ! write an equation for the interior angles of this triangle that uses the triangle sum theorem

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.

We just started the introduction into circles and i have no idea how to do this.