Complex sentence: Horizontal tying is the practice of requiring customers to pay for an unrelated product or service together with the desired one, for example, if all of Bic's pens were sold only with Bic lighters.
Split into simpler sentences: Horizontal tying is the practice of requiring consumers to pay for an unrelated product or service together with the desired one. For example, if all of Bic's pens were sold only with Bic lighters.