Word problem for systems of equations

Question

Sarah took the advertising department from her company on a round trip to meet with a potential client. Including Sarah a total of 13 people took the trip. She was able to purchase coach tickets for ​$350 and first class tickets for ​$930. She used her total budget for airfare for the​ trip, which was ​$8610. How many first class tickets did she​ buy? How many coach tickets did she​ buy?

Answer 1

c + s = 13

s = 13 - c

350c + 930s = 8610

350c + 930(13 - c) = 8610

Can you solve for c and aswer?