a climber starts descending from 504 feet above sea level and keeps going until she gets to 40 feet below sea level, how may feet did she descend?

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?

If private savings 'v' = 0.75s and total savings 's' equals $4.20 billion, solve for public and private savings.

Find the value of x for which line a is parallel to line b