To determine the number of eighth graders who took the survey, we need to add the number of eighth graders who preferred pizza to the number who preferred tacos.
From the table:
- Eighth graders who preferred pizza: 54
- Eighth graders who preferred tacos: 81
Now we can calculate the total number of eighth graders who took the survey:
\[ 54 + 81 = 135 \]
Therefore, the number of eighth graders who took the survey is 135.