I cannot understand the credit to net cost variance.

Variances, Entries, and Income Statement A summary of Martindale Company's manufacturing variance report for May follows: Standard materials cost per unit of product is 0.5 pounds at $8.40 per pound, and standard direct labor cost is 1.5 hours at $14.00 per hour. The total actual materials cost represents 4,800 pounds purchased at $8.70 per pound. Total actual labor cost represents 14,100 hours at $13.60 per hour. According to standards, variable overhead rate is applied at $1.60 per direct labor hour (based on a normal capacity of 15,000 direct labor hours or 10,000 units of product). Assume that all fixed overhead is applied to work-in-progress inventory. d. Prepare a partial income statement (through gross profit on sales) showing gross profit based on standard costs, the incorporation of variances, and gross profit based on actual costs. Do not use negative signs with any of your answers below. Variances, Entries, and Income Statement A summary of Martindale Company's manufacturing variance report for May follows: Standard materials cost per unit of product is 0.5 pounds at $8.40 per pound, and standard direct labor cost is 1.5 hours at $14.00 per hour. The total actual materials cost represents 4,800 pounds purchased at $8.70 per pound. Total actual labor cost represents 14,100 hours at $13.60 per hour. According to standards, variable overhead rate is applied at $1.60 per direct labor hour (based on a normal capacity of 15,000 direct labor hours or 10,000 units of product). Assume that all fixed overhead is applied to work-in-progress inventory. d. Prepare a partial income statement (through gross profit on sales) showing gross profit based on standard costs, the incorporation of variances, and gross profit based on actual costs. Do not use negative signs with any of your answers below