The answer is 25 because if the ratio is 4:5 and there are 20 girls that means they multiplied 4 times 5 to get 20 and that means you have to do the same to the ratio of boy and when you multiply 5 times 5 you get 25
since if you add all the following numbers up you make 11 and to taht you double the answer and that would give you 22 and then you add the remaining IP to make 25b