I need help ASAP. Pls

Which of the following circles have their centers in the third quadrant? check all that apply.

When solving a logarithm equation, how do you find the missing variable ?

While on a train trip, marsha noticed that there were 35 people in her train car. after the next stop, there were only 21 people in her car. if p represents the percent decrease in the number of people in marsha's train car, what is p?