A factory produces two types of items, Product X and Product Y. Each unit of Product X requires 3.5 labor hours to produce, and each unit of Product Y requires 5 labor hours to produce. In a particular week, the factory produced a total of 200 units of Product X and Product Y combined, utilizing a total of 800 labor hours. If $x$ represents the number of units of Product X produced and $y$ represents the number of units of Product Y produced, which of the following systems of equations can be used to determine the number of units of each product produced?