To find the ratio of the number of orders for pepperoni pizza to cheese pizza, we look at the numbers given:
- Pepperoni Pizza: 8 orders
- Cheese Pizza: 10 orders
The ratio is therefore \( \frac{8}{10} \).
To simplify this ratio, we can divide both the numerator and the denominator by their greatest common divisor, which is 2:
\[ \frac{8 \div 2}{10 \div 2} = \frac{4}{5} \]
Thus, the ratio of the number of orders for pepperoni pizza to cheese pizza is:
4:5.