需要 and 供給: the quantity needed and the quantity provided
Separate demand for goods from the provision of materials, without turning a prepared quantity into completed sales.
Demand on the needing side
需要, read じゅよう, means demand. 地域の需要に合う数だけ商品を用意した。 reports preparing a quantity of goods suited to local demand.
Demand is the basis for preparation here. The sentence does not report that all prepared goods were sold.
Supply on the providing side
供給, read きょうきゅう, means supply. 材料の供給が止まり、工場の作業が遅れた。 reports material supply stopping and factory work being delayed.
The provision of materials stopped. That does not say the demand for those materials disappeared. Need and provision describe different directions.
The scope of a quantity comparison
Under 需要は十個、供給は八個です。, the needed and provided quantities differ. Check that both use 個 before comparing them.
High demand alone does not establish completed transactions. Distinguish preparation, provision, and sale in 用意した, 供給された, and 売れた.
Does 需要に合う数だけ商品を用意した。 say that all the prepared goods were sold?
Show the answer and why
No. It reports preparing goods based on demand. Completed sales need separate confirmation.