The population in a school has a boy to girl ratio of 4 boy: 5 girls. If there are 85 girls in the school, how many are boys? Round to nearest whole boy

The ratio of boys to girls is 4 boys: 5 girls.

For every 5 girls, there are 4 boys.
If there are 85 girls, then there would be (4/5) * 85 boys.
Evaluating this expression gives (4/5) * 85 = 68 boys.
Therefore, there are approximately 68 boys in the school.