How to write expression

In the diagram, the ratio of ab to ae is (1/2) . what is the ratio of the length of to the length of ?

Find the volume of the described solid.the solid lies between planes perpendicular to the x-axis at x = 0 and x=7. the cross sectionsperpendicular to the x-axis between these planes are squares whose bases run from the parabolay=-31x to the parabola y = 30/x.a) 441b) 147c) 864d) 882

School has 204 sixth grade students. if the sixth grade is 30% of the total school, how many students are in the middle school?