Final answer:
The correct expression to describe Mary's total earnings with a fixed salary and commission is 1500 + 0.03x, where x is the amount of sales.
Step-by-step explanation:
The expression that describes Mary's salary and commission is C) 1500 + 0.03x. This is because Mary gets a fixed salary of $1500 and also earns a commission, which is 3% of her sales (x). To express a percentage as a decimal, you divide by 100, thus 3% becomes 0.03. So, for every dollar of sales, she earns an additional three cents. The expression combines her fixed salary with her commission earnings from sales (x).
With the information given, for any amount of sales that Mary makes, you simply multiply that amount by 0.03 and add it to her fixed salary of $1500 to find her total earnings. Therefore, if x represents the amount of sales, the correct expression is 1500 + 0.03x.