If you are trying to find the value of n you need to first make an equation.
When it says "half a number n" that means that you have one half times n. Then you add 7 because it says "and 7." Finally when it says is at most that means the total. So for this equation, it would be 20. So the equation would be
Then you subtract 7 from both sides.
Then you have to multiply by the reciprocal which is 2.
Then your and 2 will cancel so you are left with: