Maths -surds pls with working out : )

Mason and christian go to the movie theater and purchase refreshments for their friends. mason spends a total of $45.75 on 3 bags of popcorn and 6 drinks. christian spends a total of $71.50 on 6 bags of popcorn and 4 drinks. write a system of equations that can be used to find the price of one bag of popcorn and the price of one drink. using these equations, determine and state the price of a drink, to the nearest cent.

Ineed to know how to write question one in mathematical terms

Solve the equation for y. -1 = 1/3y + 11. will give 5 stars if answered correctly!