Write a system of equations to describe the situation below, solve using elimination, and fill in the blanks. Mr. Chandler is the volunteer coordinator for a company that puts on running races. Last year, the company organized 9 short races and 9 long races, which required a total of 864 volunteers. This year, the company organized 12 short races and 7 long races, which required 857 volunteers in total. How many volunteers does each type of race require?