The pie chart shows the number boys, girls, men and women who were in a cinema. There were 180 girls in the cinema. How many boys were there?

1. Determine the percentage of boys from the pie chart angle

The sector for boys has a right angle ($90^\circ$).
Percentage of boys = $\frac{90^\circ}{360^\circ} \times 100\% = 25\%$

2. Find the total number of people using the girls' percentage

Girls represent $15\%$ of the total.
$15\% \rightarrow 180$
$1\% \rightarrow \frac{180}{15} = 12$
Total number of people ($100\%$) = $12 \times 100 = 1200$

3. Calculate the number of boys

Number of boys = $25\%$ of $1200$
$= \frac{25}{100} \times 1200 = 300$