a$.$ Compute the return on investment using both book and current values for each division. $($Round answers to three decimal places.$)$ For ROI calculations, Envision uses operating assets as the investment base.

b$.$ Compute the residual income for both book and current values for each division.

c$.$ Compute the economic value$-$added income for both book and current values for each division if the tax rate is $20\%$ and the weighted average cost of capital is $8\%.$

d$.$ Does book value or current value provide a better basis for performance evaluation? Which division do you consider the most successful?