Bart recorded the amount of rain that fell in a desert in each month for one year. What was the total amount of rainfall in the desert that year?
(I need the step by step explanation)

Acollege is selling tickets for a winter fund-raiser. one day, krissa sold 14 adult tickets and 8 student tickets for a total of $376. the next day, she sold 7 adult tickets and 11 student tickets for a total of $272. krissa wanted to find the price of one adult ticket, a, and the price of one student ticket, s. she wrote and solved the following system of equations.