The cost in dollars, c, of renting a carpet cleaner is given by the linear equation

c = 20 + 25x, where x is the number of days.

use this model to find the number of days it can be used for $170.
a) 4
b) 5
c) 6
d)

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?

Aline has a slope of and a y-intercept of –2. what is the x-intercept of the line?

The measure of an angle is 117°. what is the measure of a supplementary angle?