In 2010 Casey made a taxable gift of $5 million to both Stephanie and Linda (a total of $10 million in taxable gifts). Calculate the amount of gift tax due this year and Casey's unused exemption equivalent under the following alternatives. (Refer to Exhibit 25-1 and Exhibit 25-2.) (Enter your answers in dollars, not millions of dollars. Leave no answer blank. Enter zero if applicable.) b. This year Casey made a taxable gift of $15 million to Stephanie. Casey is not married, and the 2010 gift was the only other taxable gift he has ever made. Gift tax due Unused exemption equivalent $ 0