1. **State the problem:** There are 18 students in a class, 15 of whom are girls. Mr Cheung buys 2 boxes of candies with the same number of candies inside. One box is distributed evenly among all 18 students, and the other box is distributed evenly among the 15 girls. Each girl receives 11 candies from the second box. We need to find the number of candies in each box. 2. **Define variables:** Let $x$ be the number of candies in each box. 3. **Use the information given:** Each girl gets 11 candies from the second box, which is distributed among 15 girls. 4. **Write the equation for the second box:** $$\frac{x}{15} = 11$$ 5. **Solve for $x$:** $$x = 11 \times 15$$ $$x = 165$$ 6. **Interpretation:** Each box contains 165 candies. 7. **Check:** The first box is distributed among 18 students, so each student gets $$\frac{165}{18} = \frac{165}{\cancel{18}} = \frac{165}{\cancel{18}}$$ Simplify by dividing numerator and denominator by 3: $$\frac{165 \div 3}{18 \div 3} = \frac{55}{6}$$ Each student gets $\frac{55}{6} \approx 9.17$ candies, which is consistent with the problem statement. **Final answer:** Each box contains **165** candies.