The manager of a trading company wants to keep the following data about customer sales and has created the table below: Quantity Invoice Invoice # date Customer Customer Contact Item Item name ID number purchase description Chan 301 6192 409 Sugar 2789 3 44 Jan 3, 2021 Chan 301 420 Rice 1 44 6192 2789 Jan 3, 2021 Peter 302 413 Noodles 3 45 8902 2913 Jan 15, 2021 Joe 303 409 Sugar 4 46 2391 1092 Jan 20, 2021 Joe 303 413 Salt 1 46 2391 1092 Jan 20, 2021 Chan 301 409 Sugar 3 6192 2789 47 Jan 31, 2021 Required: a. Using the database provided above as an example, identify and explain the major database design problems. (10 marks) b. Recommend a relational database design that can eliminate all problems identified in part (a). (20 marks)