Which expression means the same as to increase a number by 5%?

How to do this , and can some one explain

Do some research and find a city that has experienced population growth. determine its population on january 1st of a certain year. write an exponential function to represent the city’s population, y, based on the number of years that pass, x after a period of exponential growth. describe the variables and numbers that you used in your equation.

Solve 3x-18=2y and 5x-6y=6 by elimination show work