Answer:
The correct thing to do in this instanceis to take the total number of students (40) and divide them by the total parts of the ratios combined (3:5 so 3+5=8) 40/8 then gives us 5, which lets us know that every unit in the ratio is worth 5 students. Therefore, 3:5 boys:girls means (3*5):(5*5) which gives us 15 boys and 25 girls, nicely adding up to 40
Explanation: