please help with this problem and how to get to the answer thank you

A commercial cow-calf operation maintains a 200-cow base herd with 8 herd sires that are purchased every 4 years and used annually in a single breeding group. In the past, this operation has annually spent $500 per cow exposed, including the herd sires purchased for $3,500/bull, had 86% calf crop weaned, and averaged 485 lb for calf weaning weight. This operation utilizes 2,000 acres of grazing land. Assume $168/cwt for calf prices for all weaned calves. 7. Based on the above scenario, what is the: (a) income per cow exposed, and (b) net return per cow exposed? a. b. 8. Assume through purchase of 8 different herd sires at $4,500/bull, calf crop weaned became 91% and average calf weaning weight became 505 lb; all other herd aspects and expenses remain as before. For this "new" scenario calculate: (a) annual income per cow exposed, and (b) whether or not the new or old scenario is financially better. a. b. 9. Determine the income per acre under (a) the "old" scenario in Question 7 and (b) the "new" scenario in Question 8. a. b