Final answer:
To find the amount spent on oranges, define the price per pound with a variable 'p' and multiply by the weight, resulting in the expression for total cost: 7.5 x p.
Step-by-step explanation:
To calculate the amount spent on oranges, you need to define the price per pound as a variable and then multiply this variable by the weight of the oranges to get the total cost. Let's define the variable p to represent the price per pound of oranges. Using this variable, the expression for the amount spent would be 7.5 × p.