given the question : " The local transit authority has received a grant to expand its bus fleet by 30%. This expansion will provide the opportunity for approximately ten new service routes. Suggest how an optimization model might be structured to assist with the design of these new routes and the modification of existing routes. Put another way, what are the objectives, constraints, and decision variables? "

I've come up with goals and restraints :

goals : 1) accompdate a larger number of people than present

2) plan routes in coordination

restrictions: 1) no conversion of routes 2) no more than 5% of added pollution to the environment

what should i add in order to turn this into a mathematical model? and how to do it