1. **State the problem:** A school has 600 students, 330 of whom are girls. We need to find the fraction of students who are boys in simplest terms. 2. **Identify the total number of boys:** Total students = 600, girls = 330, so boys = $600 - 330 = 270$. 3. **Write the fraction of boys:** Fraction = $\frac{\text{boys}}{\text{total students}} = \frac{270}{600}$. 4. **Simplify the fraction:** Find the greatest common divisor (GCD) of 270 and 600. 5. **Calculate GCD:** $\gcd(270,600) = 30$. 6. **Divide numerator and denominator by GCD:** $$\frac{\cancel{270}^{9}}{\cancel{600}^{20}} = \frac{9}{20}$$ 7. **Final answer:** The fraction of students who are boys in simplest terms is $\frac{9}{20}$.