Answer :

The child-adult ratio in the buss is 2:5, you can express it as a fraction

[tex]\frac{2}{5}[/tex]

To determine the number of adults there are, when there are 18 kids in the bus, multiply the number of kids by the determined fraction

[tex]\frac{2}{5}\cdot18=45[/tex]

There are 45 adults on the bus