Write a system of inequalities that describes the possible solutions to each problem and graph the solution set to the system.
Political Correctness A political party is selling 50 dollars tickets and 100 dollars tickets for a fund-raising banquet in a hall that cannot hold more than 500 people. To show that the party represents the people, the number of 100 dollars tickets must not be greater than $20 \%$ of the total number of tickets sold. How many tickets of each type can be sold?