15x - 12y =13
30x +9y =4
whats the value of x

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 of the following statements must be true about this diagram? check all that apply. x°, y°, z°, & w°

The elmina wilson company produces spaghetti sauce that is used in restaurants. the fixed costs total $1,329,050. the selling price per 64 oz. can of sauce is $12.40. the variable cost per can is $4.80. what is the break-even point in number of cans?