To find out how many pieces Cole will be able to sing after 28 weeks of voice lessons, we can substitute \( w = 28 \) into the equation \( p = w + 34 \).
Substituting \( w \) into the equation:
\[ p = 28 + 34 \]
Now, calculate the total:
\[ p = 62 \]
Therefore, after 28 weeks of voice lessons, Cole will be able to sing a total of 62 pieces.