Final answer:
Dana can contribute up to $5,500 to a Roth IRA in 2015.
Step-by-step explanation:
In 2015, Dana can contribute up to $5,500 to a Roth IRA. The maximum contribution limits for IRAs can change each year, but for 2014 and 2015, the limit is $5,500. If Dana is 50 years old or older, she can contribute an additional $1,000 as a catch-up contribution, bringing the total limit to $6,500. Since Dana's AGI is $120,000, she is eligible to contribute the maximum amount of $5,500 to a Roth IRA in 2015.