Answer:
Explanation:
Since in the given question, the action real estate has received a check of $18k on July 1 which represents a 6 month advance payment. That means, we have to calculate for full year payment instead of 6 month.
So,
For  a year = ( Amount × 12 months ) ÷ 6 months
         = $18 k × 12 ÷ 6
         = $36 k
Now, we have to find for 1 month because the adjusting entry was made on July 31 and the check is received on July 1.
So ,
1 month =  Yearly Amount ÷ Total months in a year
       = $36 k ÷ 12 months
       =$3 k
Hence, the adjusting entry would be :
Unearned Rent A/c Dr   $3 k
  To Rental revenue          $3 k
(Being adjusted entry recorded)