<h2>Addition</h2><h3>Concept</h3>
Add units together in order to reach a sum.
<h3>Utilization</h3>In this problem, you are told to find the probability (or %) that someone owns either a dog, OR a cat. If they own both - then they do in fact own a dog or cat. So the formula is:
dog owners % + cat owners % + both owners %
Aka,
The answer is 46% of people own either a cat or a dog, because 23% + 18% + 5% is 46%.