Which of the following equations represents a line with a positive slope and a negative y intercept? A - y = 3.5x
B - y = 7.5x - 2
C - y = 1/4x + 7
D - y = -5x - 8

(2,20) means that the 2 is 2 hours and 20 is 20$. so there both 20$ for 2 hours only the same price. like it says. so, the dunk tank and the bounce house are the same price (20$) for the same amount of time (2 hours).

hope i

the formula of a slope:

we have the points (-2, 7) and (2, 3). substitute:

ending amount = beginning amount / (2^n)

where "n" = number of half-lives (or elapsed time / half-life)

ending amount = 50 mg / (2 ^10 / 5.3)

ending amount = 50 mg / (2 ^ 1.8867924528)

ending amount = 50 m / 3.6981210597

ending amount = 13.5203794557 mg

or about 13.5 mg remain

source:  

any of them that add up to 180 degrees.