1. The problem asks to find the percentage of problems Olivia got correct out of 20 assigned problems. 2. The formula to find percentage is: $$\text{Percentage} = \left(\frac{\text{Number of correct problems}}{\text{Total problems}}\right) \times 100$$ 3. Substitute the given values: $$\text{Percentage} = \left(\frac{13}{20}\right) \times 100$$ 4. Simplify the fraction: $$\text{Percentage} = \left(\frac{\cancel{13}}{\cancel{20}}\right) \times 100 = 0.65 \times 100$$ 5. Multiply to get the percentage: $$0.65 \times 100 = 65$$ 6. Therefore, Olivia got 65% of the problems correct.