Cost of equity be if the debt-equity ratio

Question

Crosby Industries has a debt-equity ratio of 1.5. Its WACC is 8.5 percent, and its cost of debt is 6 percent. There is no corporate tax.

Required:

• What would the cost of equity be if the debt-equity ratio were 2.0?
• What would the cost of equity be if the debt-equity ratio were 0.5?
• What would the cost of equity be if the debt-equity ratio were zero?

Note: Please show how to work it out.