Capital Gain Tax Problem

In 2015, Wes sells shares of stock in IBM for $20,000. He purchased the IBM stock for $18,000 two years
ago. Wes’ taxable income on line 43 of his IRS Form 1040 is $100,000. Wes is single.   

Calculate Wes’ tax liability (line 44 of IRS Form 1040) for 2015. In providing your answer, include an IRS Form 1040 and any appropriate Schedules and worksheets.

If you need to make any assumptions to support your answer, please state those clearly in your answer.