We are asked to determine the probability of rolling a 1 or a 6. To do that we will use the following relationship:

Therefore, we need to add the probability of getting a 1 and the probability of getting a 6.
The probability is the quotient of the number of occurrences divided by the sum of the total number of occurrences, like this:

Solving the operations:

Now, we determine the probability of getting a 6:

Now, we add the probabilities:

The probability is 11/20.