(pls answer this) (no links) (pls explain )

What is the interquartile range of this data set? 2, 5, 9, 11, 18, 30, 42, 48, 55, 73, 81

Which steps could be part of the process in algebraically solving the system of equations, y+5x=x^2+10 and y=4x-10

I’m on question 7 it says a covered water tank is in the shape of a cylinder the tank has a 28 inch diameter and a height of 66 inches to the nearest square inch what is the surface area of the water tank