Sharon was visiting a local farmer's market. The sign advertised apples 10lb. for $4.00. Based on the sign, what is the unit rate for apples?
HELP I HAVE NO KNOWLEDGE WHATSOEVER 

Aflute is on sale for 20% off. including the discount and 8% tax, the sales price is $216.

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

Determine which expressions represent real numbers and which expressions represent complex number. asaaap! plis!