How do I solve this problem?

How to solve a simultaneous equation involved with fractions?

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.

Find the greatest common factor of the followig monomials 21u^5v,3u^4v^6, and 3u^2v^5