please help! and simplify the answer

Answer:
3a) 4:5
4a) 1:4
Step-by-step explanation:
3a) you just find the GFC of both 12 and 15, and then use the first number for girls and 2nd for boys, in this case 4 for girls and 5 for boys giving you 4:5.
4a) You just add 4 to 12 it gives you 16 and divide 4 and 16 by 4 giving you a ratio of 1:4.