Answer:
oki! Mizuki here to help! 12 will be your answer!
Step-by-step explanation:
Soo... The ratio of blue to green is 4:3 right?
and there are 21 balloons!
4 + 3 is 7! So we divide 21 by 7 and get 3!
Then we multiply 3 by the number of blue balloons(aka 4) and get 12!
