Answer:
0.8 probability that it is large or white.
Explanation:
A probability is the number of desired outcomes divided by the number of total outcomes.
In this question:
We have 19 + 11 = 30 marbles, which means that 30 is the number of total outcomes.
We have 19 large marbles, and 5 small marbles which are white, which means that the number of desired outcomes is 19 + 5 = 24. So

0.8 probability that it is large or white.