Answer:
5:6 --> 10:12
Explanation:
A good way to think of this is to provide a perspective: there are 5 boys every time there is 6 girls. So if there is 10 boys, that means there would be 12 girls (because 5 *2 = 10 and 6*2 = 12).
tl:dr: 5 *2 = 10 so 6*2 = 12