Extra Math Practice #176-180

$y&=x^2+x-8\\y&=2x-2$

If $(x,y)$ is a solution to the system of equations above, what is the greatest possible value of $\left|x-y\right|$ ?

A)1

B)4

C)7

D)8

2 In the $xy$ -plane, line $m$ has the equation $y=-5x+a$ , where $a$ is a constant. Line $n$ passes through the origin and is perpendicular to line $m$ . If line $m$ and line $n$ intersect at the point $(15,b)$ , where $b$ is a constant, what is the value of $a$ ?

Valentina is shopping for apartments. She sees one advertisement for an apartment on Maple Street that has a total area of 715 square feet and another advertisement for an apartment on Elm Street that has an area of 200 square meters. Which of the following statements is true?

(Note: 1 foot = 0.3048 meters)

A)The area of the apartment on Maple Street is about 3 times that of the apartment on Elm Street.

B)The area of the apartment on Maple street is about 9 percent greater than that of the apartment on Elm Street.

C)The area of the apartment on Maple Street is about 8 percent less than that of the apartment on Elm Street.

D)The area of the apartment on Maple Street is about $\dfrac{1}{3}$ of that of the apartment on Elm Street

A biology teacher surprised her class today with a quiz consisting of ten questions, each worth one point. The dot plot above represents the scores of the 15 students who were present to take the quiz. One additional student who was absent today will take the quiz tomorrow. If that student's score increases the range of scores, what will be the median quiz score for the 16 students in the class?

$x-1=\dfrac{8}{x+1}$

What is the sum of all values of $x$ that satisfy the equation above?

A)–1

B)0

C)1

D)3