Can someone explain how to solve this

Which of the following answers is 7/9 simplified? 7/9 2/9 11/9 2/7

For each proportion find the unknown number x 1/5/8=×/15

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