To predict how many 7th graders would choose pepperoni as their favorite pizza topping, we can use the proportion of students who chose pepperoni in Angel's survey.
Angel asked 100 students, and 34 of them chose pepperoni. The proportion of students who chose pepperoni is:
\[ \frac{34}{100} = 0.34 \]
Now, we can use this proportion to estimate how many 7th graders out of the entire school of 450 would choose pepperoni:
\[ 0.34 \times 450 = 153 \]
Therefore, Angel could predict that approximately 153 7th graders would choose pepperoni as their favorite pizza topping.