To expand this expression, you must use the distributive property to multiply everything inside the parentheses by 1/6. So your expression should look like this:
(1/6 * 18x) - (1/6 * 24)
Now multiply 18x and 24 by 1/6 and rewrite your expression. Your expression should look like:
(3x) - (4)
After applying the distributive property, you're finished. You've expanded your expression, so your answer to this question would be 3x - 4.