When you're signed into your return, go up into the upper margin of the screen and click on My Account, then select Tools from the dropdown menu. When the Tools Center appears, click on the first item in the list of Other Helpful Links, View Tax Summary. Then look above the summary page and click on Preview My 1040. This will load the 2-page 1040 for you to review.
You'll see the AGI figure on line 37 (line 21 if 1040A).
Here's a link to the IRS page discussing IRA deduction limitations: https://www.irs.gov/retirement-plans/ira-deduction-limits
