Complex sentence: In the majority of the cases, the office will convince businesses that it is in their own financial interests to respect the francophone customers, as they constitute roughly 80% of the province's population.
Split into simpler sentences: In the majority of the cases, the office will convince businesses that it is in their own financial interests to respect the majority of the customers (who speak French). Generally, businesses opt to cater to francophone customers, as they constitute roughly 80% of the province's population.