FORMULAS
If A and B are any events then:

If A and B are mutually exclusive events then P(A and B) = 0, so then:

The probability of an event happening is given to be:

SOLUTION STEPS
The total number of pets in the store is calculated to be:

The probability of picking a puppy is:

The probability of picking a kitten is:

Therefore, the probability of choosing a puppy or a kitten is gotten to be:

ANSWER
The probability is 3/4 or 0.75.