Unida Systems has $42$ million shares outstanding trading for $$$$8$ per share. In$$ addition, Unida has $$$$84$ million in outstanding debt. Suppose Unida$\text{'}$s equity cost of capital is $18\%,$ its debt cost of capital is $7\%,$ and the corporate tax rate is $25\%.$

a$.$ What is Unida$\text{'}$s unlevered cost of$$ capital?

b$.$ What is Unida$\text{'}$s $$after$-$tax debt cost of$$ capital?

c$.$ What is Unida$\text{'}$s weighted average cost of$$ capital?