You are asked to value a Merger and Acquisition deal using a Black-Schole model. Firm A and B plan to merge into Firm AB.

Prior to the merger, information for firm A and B are as follows:

Firm A: market value of firm's assets is 15 $billion; face value of firm's zero coupon bdebt is 7 $billion; standard deviation of firm's asset return is 35% .

Firm B: market value of firm's assets is 9 $billion; face value of firm's zero coupon bdebt is 3 $billion; standard deviation of firm's asset return is 45% .

The maturity of firm's zero coupon debt is 5 years.

Risk free rate is 3% .

After the merger, the standard deviation of firm's asset is reduced to 28% per year.

Use Black-schole model to find out the market value of equity after the two firms merged: ________ ($billion)

(Please DO NOT round your intermediate steps, and format and round your FINAL answer to billion of dollars with ONE decimal place: for example, 12.3 only)