Because you are not at least 65 years old by the end of the year, you apply the 10% threshold to all of your itemized medical costs (which include costs related to your mother). If she claimed them on her own return, she could apply the 7.5% threshold.
The difference between amount realized and adjusted basis on the sale or exchange of capital assets. Long-term capital gains are taxed favorably. Capital losses are deducted first against capital gains, and then again up to $3,000 of other income.