Let n is an unknown number.

The word twice a number n represents .

The word is more than represents .

The word the sum of number n and 9 represents .

The word Twice a number n is more than the sum of number n and 9. represents .

The inequality is .

Apply subtraction property of inequality: If .

Subtract n from each side.

Apply commutative property of addition: If .

The solution set is .

Check:

To check, substitute three different values for n into the original inequality: 9, a number less than 9, and greater than 9.

Let three values are .

If then            (This is false)

If then            (This is false)

If then   (This is true)

The inequality is and the solution set is .