The Augment Manufacturing Company Has Three Divisions: X Division, Y

The Augment Manufacturing Company has three divisions: X Division, Y Division, and Z Division. Operating results for the three divisions for last year were as follows:
$\begin{array}{c}\begin{array}{lrr} \text { Residual income } &\\ \text { Net operating income } &\\ \text {Average operating asset: } &\\ \text { Sales } &\\ \text { Profit margin } &\\\end{array}\begin{array}{ccc}\text { Division } \mathrm{X} & \text { Division Y } & \text { Division Z } \\\$ 98,400& \$27,200 &\$ 12,000 \\188,600 & 115,600& 76,000 \\ 820,000 & 680,000 & 400,000 \\ 1,640,000 & 1,445,000 & 1,040,000 \\ 11.5 \% & 8.0 \% & 5 .0\% \\\end{array}\end{array}$

Required:
a. What is the ROI for each of the three divisions?
b. What is the cost of capital for each of the three divisions?