Anthony sold 45 tickets to the school play and Katy sold 40 tickets. What is the ratio of the number of tickets Anthony sold to the number of tickets Katy sold? A 9:8 B 40:45 C 5 to 8 D 8 to 9

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?

1mile equals approximately 1.6 kilometers. which best approximates the number of miles in 6 kilometers?

Which of the following is an equation of a line parallel to the equation y=4x+1?