Answer:
There would be 18 boys.
Explanation:
If the ratio of boys to girls is 3:4 that means in a classroom of 7 people there would be 3 boys and 4 girls. So all you do is multiply 3 boys by 6 (18) and 4 girls by 6 (24) cuz 7*6=42 which means that there would be a total of 42 students with 18 boys and 24 girls.