Answer:
The probability that she will catch a T-shirt that is not a size small is 
Step-by-step explanation:
Here, the total number of shirts thrown in the crowd = 50
The number of small shirts thrown = 10
The number of medium shirts thrown = 15
The number of large/ extra large shirts = Total shirts - ( 10 + 15)
= 50 - 25 = 25
So, in total 25 shirts are thrown in the crowd of large/extra large.
Now, the number shirts which is NOT SMALL size
= Total shirts - Shirts with small size = 50 - 10 = 40

Hence, the probability that she will catch a T-shirt that is not a size small is 