On January 1, 2011, DeSoto Industries' accumulated postretirement benefit obligation was $75 million. Retiree benefits of $9 million were paid at the end of 2011. Service cost for 2011 is $21 million.

Estimates and assumptions regarding future health care costs were revised in 2011, causing the actuary to revise downward the estimate of the APBO by $2 million. The actuary's discount rate is 8%. There were no unrecognized postretirement benefit costs at the end of 2011.

What is the accumulated postretirement benefit obligation at December 31, 2011?

Explanation: The APBO ($75) is increased by the service cost ($21) and the interest expense ($6 = 8% x 75), and decreased by the benefits paid ($9) and the estimation revision ($2) [in millions].