Partial Roth Conversion - entering taxable amount

I had 80k in a Personal IRA with both Deductible/non-deductible contributions
I converted 40K  of which only 22k is Taxable .
I received  a 1099-R from the brokerage house with the following
Box1 - 40k
Box 2 - Taxable amount 40k
Box 2b Taxable amount not determined is Checked
Box 7 distribution code - 7 / IRA  checked
The taxable portion is only around 22k  and i am not able to input this in Turbotax. Can someone help please