Whos good with proofs ?

given: 7y−84=2y+61

prove: y=29

step reason

7y−84=2y+61

5y−84=61

5y=145

y=29

find the reasons with these below

multiplication property of equality

symmetric property

simplify

given

division property of equality

distributive property

addition property of equality

subtraction property of equality

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

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?

How many verticies does a triangular prims have