A history teacher is writing a test worth 100 points. She uses multiple-choice questions worth 6 points each and true/false questions worth 2 points each. She wants the test to have three times as many multiple-choice questions as true/false questions. Let m represent the number of multiple-choice questions on the test, and let t represent the number of true/false questions. Which system of equations can be used to find how many of each type of question she should write.