A computer software salesman earns a base salary of $28,000 per year and a graduated commission. For all yearly sales from $0 to $5000, he receives a commission of 10%; for all yearly sales from $5000 to $10,000, he receives a commission of 15%; for all yearly sales from $10,000 to $50,000, he receives a commission of 25%; and for all yearly sales above $50,000, he receives a commission of 30%. The salesman expects to make $80,000 in sales this year, and wants to calculate his projected yearly earnings. (5 points: Part I - 1 point; Part II - 1 point; Part III - 1
point; Part IV - 1 point; Part V - 1 point)

Part I: How much will the salesman earn in commission on the first $5000 of his sales?

Part II: How much will the salesman earn in commission on his sales from $5000 to $10,000?

Part III: How much will the salesman earn in commission on his sales from $10,000 to $50,000?

Part IV: How much will the salesman earn in commission on his sales above $50,000?

Part V: What are the salesman's projected yearly earnings?