The value of

A theater charges $8 for main floor seats and $5 for balcony seats, If all the seats are sold, the ticket income of $4200. At one show, 25% of the main floor seats and 40% of the balcony seats were sold and the ticket income was $1200. How many of the seats are in the main floor and how many are in the balcony

a) Set up the system of equations

b) Solve the system in the any method of your choosing

Show work, please.