Answer: 
$124,000 
Explanation: 
The computation of ending balance in the land account is shown below:- 
ending balance in the land account = Beginning balance of Land account + Total balance of land - Cost of land sold 
= $90,000 + ($25,000 + $28,000 + $31,000) - $50,000 
= $90,000 + $174,000 - $50,000 
= $124,000 
Therefore for computing the ending balance in the land account we simply applied the above formula.