Calculate the rate of return available to shareholders for a company financing $1 million of assets with the following three arrangements:

a. All equity

b. 50% equity, and 50% debt at an interest rate of 12% per annum.

c. 25% equity, and 74% debt at an interest rate of 12% per annum.

The assets are expected to generate earnings before interest of $150,000 per annum in perpetuity.

Show all relevant calculations and formulas.