Answer:
No. of boys = 15
Explanation:
Given that,
The ratio of boys to student is 3:7.
Number of girls in the school = 20
We need to find the number of boys in the school.
Let there are 3x boys and 7x number of students.
No. of girls = Total students - no. of boys
= 7x-3x
= 4x
ATQ,
4x = 20
x = 5
No. of boys = 3x
= 3(5)
= 15
Hence, there are 15 boys in the school.