Answer:
Blue marbles are 100.
Explanation:
Number of red marbles=252 × 2/7
Number of red marbles=72
Remaining marbles=252-72
Remaining marbles=180
Now,
Number of green marbles=180×4/9
Number of green marbles=80
Reaminng marbles which are blue=100-80
=100
If you have any questions about it let me know.