Ratio

At camp today, kids can choose art, swimming, or music. Of those activities, 40 kids choose swimming, 16 choose art, and 24 choose music. What is the ratio of kids who choose art to kids who choose swimming?

kids who choose art : kids who choose swimming = $\frac{16}{ 40}=\frac{2\cdot 8}{ 5\cdot 8} = \frac25$