1. The problem is to find the overall average percentage when you have 90% in 3 classes and 65% in 1 class. 2. The formula for the average percentage is: $$\text{Average} = \frac{\text{Sum of all percentages}}{\text{Number of classes}}$$ 3. Calculate the sum of all percentages: $$3 \times 90 + 1 \times 65 = 270 + 65 = 335$$ 4. Calculate the number of classes: $$3 + 1 = 4$$ 5. Calculate the average: $$\frac{335}{4}$$ 6. Simplify the fraction: $$\frac{\cancel{335}}{\cancel{4}} = 83.75$$ 7. So, the overall average percentage is **83.75%**.