THIS MIGHT SURPRISE YOU
The answer
Agree. The majority view, called Markan priority, is that Mark was written first and used as a source by Matthew and Luke. It's one of the more settled conclusions in Gospel studies, though not universally held.
Why it’s interesting
Matthew and Luke reproduce most of Mark, often word-for-word, while smoothing his rougher Greek — evidence that runs in one direction. This ordering is the doorway to the whole "synoptic problem" you'll meet higher up the ladder.
Scholarly consensus
You can know the Bible.
Not just the stories, but the history, authorship, and scholarship behind it.