IDNLearn.com: Your one-stop destination for finding reliable answers. Get the information you need from our community of experts who provide accurate and thorough answers to all your questions.

A used book store started selling CDs and videos. In the first week, the bookstore started selling 40 CDs and videos. They charged $4 per CD and $6 per video. The total sales was $180. Which system of equations corresponds to this situation?