What is the binomual coefficient for the first term if contains only variables?

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

How to choose the sign of the radical in the denominator of the formula for the distance from a point to a line.

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