Help plz ??

This is really urgent. If anyone knows the answer plz plz help me

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

Four airplanes carrying a total of 400 passengersarrive at the detroit airport. the airplanes carry, respectively,50, 80, 110, and 160 passengers.a) one of the 400 passengers is selected uniformly at random.let x denote the number of passengers that were on theairplane carrying the randomly selected passenger. find var(x)for x as given in the problemb) one of the 4 airplane drivers is also selected uniformly atrandom. let y denote the number of passengers on the chosen driver’s airplane. find var(y) for y as given in the problem

Find the difference (8ab+a+2) - (3ab+6)