Jeremiah can type 300 words in 1/5 of an hour, how many words can he type in 2/3 of an hour

Here is their argument. given the obtuse angle x, we make a quadrilateral abcd with ∠dab = x, and ∠abc = 90◦, and ad = bc. say the perpendicular bisector to dc meets the perpendicular bisector to ab at p. then pa = pb and pc = pd. so the triangles pad and pbc have equal sides and are congruent. thus ∠pad = ∠pbc. but pab is isosceles, hence ∠pab = ∠pba. subtracting, gives x = ∠pad−∠pab = ∠pbc −∠pba = 90◦. this is a preposterous conclusion – just where is the mistake in the "proof" and why does the argument break down there?

What adds to be the bottom number but also multiplies to be the top number with 8 on the bottom and 15 on top

The measurement of one angle of a right triangle is 42° what is the measurement of the third angle? (there is no picture)