In a school, 40% of the pupils are boys.
5% of the boys and 20% of the girls walk to school.
What percentage of the pupils in the school walk to school?

1. Find the percentage of girls in the school

Percentage of girls $= 100\% - 40\% = 60\%$

2. Calculate the percentage of total pupils who are boys that walk

Boys who walk $= 5\% \text{ of } 40\% = \frac{5}{100} \times 40\% = 2\%$

3. Calculate the percentage of total pupils who are girls that walk

Girls who walk $= 20\% \text{ of } 60\% = \frac{20}{100} \times 60\% = 12\%$

4. Find the total percentage of pupils who walk to school

Total percentage $= 2\% + 12\% = 14\%$