Please explain why & how the answer is $92,200

1. The following information pertains to Hopson Co.'s pension plan: Actuarial estimate of projected benefit obligation at 1/1/13 $72,000 10% $28,000 $15,000 Assumed discount rate Service costs for 2013 Pension benefits paid during 2013 If no change in actuarial estimates occurred during 2013, Hopson's projected benefit obligation at December 31, 2013 was a. $74,200. b. $85,000. c. $90,200. d. $92,200