can you tell me the difference between perpetual and not perpetual ? and show all the work

Your all equity firm has a price per share of $18 and has 7M shares outstanding. Suppose the firm issue $12M worth of debt. The debt has a face value of $12M, a coupon rate of 7 percent, and 8 years until maturity. The expected return on the debt is 7 percent. Assume a corporate tax rate of 35%. If the debt were perpetual, what would be the new share price after the debt issuance? A.18.25 B.18.00 C.18.60