Explanation:
I do not know the rest of the question (answer choices), however, what you want to do with this equation is put it into slope-intercept form to be able to test which points might lie on that line.
3x + 7y = 21
7y= -3x + 21
y= -3/7x + 3
Now, you want to plug in your values to see which set this equation satisfies.
