I already solved a, need help with b,c,d. data is in the first picture.

E2 Xfx=RATE(20,0,B2,B21) b. Based on the data, what is the estimated Cobb-Douglas production function for the company? Is the company an increasing return to scale? Why or why not. c. Using the estimated Cobb-Douglas production function, and given the cost of labor as $25,000 per year and capital as $5,000 per unit, what is the expansion path (optimal mix of labor and capital)? d. Using the estimated production function, determine how much labor and capital should have used each year