To find out how many weeks of voice lessons Tucker needs to take in order to sing a total of 18 pieces, we can set up the equation based on the formula given:
\[ p = w + 2 \]
We know that \( p = 18 \) (the total number of pieces he wants to learn). Substituting 18 for \( p \) in the equation gives:
\[ 18 = w + 2 \]
To solve for \( w \), we subtract 2 from both sides:
\[ 18 - 2 = w \] \[ 16 = w \]
Therefore, Tucker will need to take 16 weeks of voice lessons before he can sing a total of 18 pieces.