Final answer:
Brenda spent $4,350 on fabric.
Step-by-step explanation:
To determine how much Brenda spent on fabric, we first need to find out how much black fabric she bought. It is given that Brenda bought three times more black fabric than red fabric. Since she bought 72 inches of red fabric, we can calculate 3 times 72 to find out the amount of black fabric: 3 * 72 = 216 inches.
Next, we need to convert the fabric measurements from inches to yards, as the fabric costs $725 per yard. There are 36 inches in a yard, so we can divide the amount of black fabric in inches by 36 to get the amount in yards: 216 / 36 = 6 yards.
Finally, we can calculate the total amount Brenda spent on fabric by multiplying the amount of black fabric in yards by the cost per yard: 6 * $725 = $4,350.