Answer:
n = 4
Explanation:
Let's put all of our variables on one side, and all of our non-variable numbers on the other. (I like to do this so that the variable isn't negative. You'll still get the same answer.)
So we can minus 2n on both sides, giving us 7 = n + 3.
Then, let's do our non-variables and subtract 3 from each side. This gives us 4 = n or n = 4.
Therefore, n = 4.