Liliana made an error while solving the equation. Let's go through the steps to identify the correction she needs to make.
The original equation is: One-third (x + 18) = 7
Step 1: Distribute the one-third to the terms inside the parentheses.
One-third x + 6 = 7
Step 2: Isolate the variable by subtracting 6 from both sides.
One-third x + 6 minus 6 = 7 minus 6
One-third x = 1
So far, Liliana's steps are correct.
Step 3: To solve for x, we need to multiply both sides of the equation by the reciprocal of one-third, which is 3.
(One-third x) * 3 = 1 * 3
x = 3
Liliana's final answer is correct. She does not need to make any corrections.
Therefore, the correct answer is: The final step should be x = 3.
I hope this helps!