How can i find out what fraction is the largest?

: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?

The area of a rectangle is 10 cm^2. one side of the rectangle is x cm. express the perimeter of the rectangle in terms of x and show that this rectangle cannot have a perimeter of 12 cm. the perimeter of the rectangle in terms of x is __ cm

Write as a product: ac^2–ad+c^3–cd–bc^2+bd