Can someone could explain the part of simplifying rational expressions where it is x is not equal to a number. I've had a hard time understanding how to get that answer. The picture is an example in my notes.

The graph shows the distance y, in inches, a pendulum moves to the right (positive displacement) and to the left (negative displacement), for a given number of seconds x. how many seconds are required for the pendulum to move from its resting position and return? enter your answer in the box.

:24% of students in a class are girls. if there are less than 30 students in this class, how many students are there? how many girls are there?

Type the correct answer in each box. use numerals instead of words. if necessary, use / fir the fraction bar(s). the graph represents the piecewise function: h