Answer:
165 ways
Step-by-step explanation:
Total number of painting, n = 11
Now, three of them are chosen randomly to display in the gallery window.
Hence, r = 3
Since, order doesn't matter, hence we apply the combination.
Therefore, number of ways in which 3 paintings are chosen from 11 paintings is given by

Formula for combination is 
Using this formula, we have

Therefore, total number of ways = 165