Please help it’s a quiz and can you show me an example how to do this ? And the answer please?

Isee the amount was $90.00 then reduced to $75.00 , what is the percent ?

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 of the following correctly justifies statement four of the two column proof? a. corresponding angles theorem b. transitive property of equality c. vertical angle theorem d. substitution property of equality