A science class has girls and boys in the seventh grade and girls and boys in the eighth grade. The teacher randomly selects a seventh-grader and an eighth-grader from the class for a competition. What is the probability that the students she selects are both boys?
Write your answer as a fraction in simplest form.

One expression below in undefined, and the other expression has a well defined value. which expression is undefined and explain why it has no value. which expression is defined? what is the value of that expression and how do you know? what is a different expression using a trig inverse function that is also undefined?

Acylinder and its dimensions are shown. which equation can be used to find v, the volume of the cylinder in cubic centimeters?

How can you tell when x and y are not directly proportional?