#3 and #9 geometry !! Pls help

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

Which statement justifies why angle ebc measures 90?

Which word in the sentence below is an interrogative pronoun? who is picking us up from school? whousisfrom