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