Please only do a) :)​

Asoccer ball manufacturer wants to estimate the mean circumference of soccer balls within 0.1 in

There were 816 people at a concert when a band started to play. after each song, only half the people stayed to hear the next song. how many people were left at the concert after x songs? write a function to represent this scenario.

Asystem of equations has 1 solution.if 4x-y=5 is one of the equations , which could be the other equation ?