Depriciation and revaluation and Disposl

Sir, my answer was not matching in this Q. Let me show you . Q---> On 31 January 2018 westvale company disposed of a building for $450,000. the building was accounted for using the valuation model. At the date of disposal, after the deduction of accumulated appreciation of 90,000, the building had a carrying value of $310,000 it had a revelation surplus in equity of 30,000. What was the westvale's profit on disposal of building for inclusion in statement of profit and loss for the year ended 31 December 2018 ? How I solved ---> profit = Proceeds - Carrying value . Profit = 450,000 - 310,000 = 140,000 But the answer on exam kit is - 50,000 . I don't understand why. There is no explanation