Can someone please tell me how to subtract 1 3/8 by 3/4

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?

This race was first held in 1953 on august 16th. every decade the race finishes with a festival. how many years is this?

30 pts, will mark brainliestwhat is the period of the sinusoidal function? (picture 1)what is the minimum of the sinusoidal function? (picture2)what is the maximum of the sinusoidal function? (picture 3)