In which expression is the coefficient of the n term -1

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?

Which shows the correct lengths of side c in both scales? scale 1: 45 m; scale 2: 60 m scale 1: 60 m; scale 2: 45 m scale 1: 36 m; scale 2: 27 m scale 1: 27 m; scale 2: 36 m mark this and return save and exit

What is the area of mnp? 40 m2 60 m2 68 m2 127.5 m2