Final answer:
The total cost of Andre's purchases, including a 10% sales tax, is calculated by the expression (5x + 6y) + (5x + 6y)(0.10), which corresponds to option C.
Step-by-step explanation:
The question asks us to find an expression that can be used to calculate the total cost of Andre's purchases, including a 10% sales tax. To find the total cost before tax, you multiply the quantity of the items purchased by their respective costs per unit: 5 pounds of bananas at x dollars per pound and 6 pounds of apples at y dollars per pound. This gives us the expression 5x + 6y.
To include the 10% sales tax, you would take the total cost before tax, (5x + 6y), and add 10% of this cost to it. Therefore, to calculate the total cost with tax, the correct expression is (5x + 6y) + (5x + 6y)(0.10), which matches with option C. This expression accounts for both the initial cost of the fruits and the additional cost due to sales tax.