25/10x4=10 boys
100%-40%=60%
25/10x6= 15
boys:girls
10:15
<u><em>Answer:</em></u>

<u><em>Explanation:</em></u>
<u>The given equation is:</u>

To get the value of B, we will need to isolate it on one side of the equation
<u>This is done as follows:</u>
<u>1- Multiply both sides by
to get rid of the fraction:</u>

<u>2- Add 25 to both sides of the equation:</u>

Based on the above:

Hope this helps :)