15. A lawn is 21 feet wide and 39 feet long. How much will it cost to weed and feed it if a gardening service charges \( \$ .40 \) per square yard for this treatment?

To find the cost of weeding and feeding the lawn, we need to calculate the area of the lawn first. Given: - Width of the lawn = 21 feet - Length of the lawn = 39 feet The area of the lawn can be calculated using the formula: \[ \text{Area} = \text{Width} \times \text{Length} \] Substitute the given values into the formula: \[ \text{Area} = 21 \times 39 \] Now, we need to convert the area from square feet to square yards. Since 1 yard is equal to 3 feet, we can convert the area as follows: \[ \text{Area in square yards} = \frac{\text{Area in square feet}}{9} \] After finding the area in square yards, we can calculate the cost by multiplying the area by the cost per square yard. Let's calculate the area and then the cost. Calculate the value by following steps: - step0: Calculate: \(21\times 39\) - step1: Multiply the numbers: \(819\) Calculate or simplify the expression \( 819/9 \). Calculate the value by following steps: - step0: Calculate: \(\frac{819}{9}\) - step1: Reduce the numbers: \(\frac{91}{1}\) - step2: Calculate: \(91\) The area of the lawn is 819 square feet, which is equivalent to 91 square yards. Now, we can calculate the cost of weeding and feeding the lawn by multiplying the area in square yards by the cost per square yard. Cost = Area in square yards * Cost per square yard Cost = 91 * $0.40 Cost = $36.40 Therefore, it will cost $36.40 to weed and feed the lawn.