How do you solve problems like this?

If x + 10 = 70, what is x? a. 40 b. 50 c. 60 d. 70 e. 80

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

60 2(x + 2) in the diagram, gef and hef are congruent. what is the value of x?