8. Mr. Wilson's class took an exam consisting of multiple choice and fill-in-the-blank questions. It takes Katie 2 minutes to answer a multiple choice question and 4 minutes to answer a fill-in-the-blank question. Katie finished the exam in 140 minutes. It takes Robert 5 minutes to answer a multiple choice question and 6 minutes to answer a fill-in-the-blank question. Robert finished the exam in 250 minutes. Which system of equations below can be used to determine the number of multiple choice and fill-in-the-blank questions that were on the exam?

(Let x represent the number of multiple choice questions and y represent the number of fill-in-the-blank questions.)