sufficient by; resolve by~
Says that something can be settled or resolved with a lesser action or cost than expected.
This pattern expresses that a problem or obligation can be resolved with a small effort, a small amount of money, or a simple action. It often carries a sense of relief that things didn't turn out worse. For example, if you broke someone's phone but a simple apology fixed it, you'd say 謝って済んだ. The past form 済んだ is common in conversation, and the present form 済む is used for general statements or future. The negative form 済まない means it can't be resolved that way, often implying you need to do more. This is a standard spoken and written pattern, but it's not overly formal. Note that with nouns, you use で済む, not て済む.