Liliana solved the equation below. When she tried to verify her answer, she realized she made an error.

One-third (x + 18) = 7
One-third x + 6 = 7
One-third x + 6 minus 6 = 7 + 6
One-third x = 1
x = 3

Which correction should Liliana make?
The first step should be One-third x + 54 = 7.
The second step should be One-third x + 6 minus 6 = 7 minus 6.
The third step should be One-third x = 13.
The final step should be x = one-third