According to the given information, the supplies beginning balance as on Feb. 1 2016was $1400 and Supplies purchase during the February month were total $12,000 and the supplies ending balance as, on Feb. 29, 2016, is $1,500. It means the supplies used is = 1400+12000-1500 = $11,900.
Adjusting journal entry at the end of the month shall be as follows:
Date: Feb. 29, 2016:
Supplies Expense Debit $11,900
Supplies Credit $11,900