I found this question is tough .. can anyone help me to solve it
and explain the answer for me
![Smile :)](./images/smilies/smile.png)
At the beginning of the year, the ratio of juniors to seniors in high school X was 3 to 4. During the year, 10 juniors and twice as many seniors transferred to another high school, while no new students joined high school X. If, at the end of the year, the ratio of juniors to seniors was 4 to 5, how many seniors were there in high school X at the beginning of the year?
a) 80
b) 90
c) 100
d) 110
e) 120