A partial adjusted trial balance of Gehring Company at January 31, 2015, shows the following.
Assuming the year begins January 1.

GEHRING COMPANY
Adjusted Trial Balance
January 31, 2015
Debit Credit
Supplies $850
Prepaid Insurance 2,400
Salaries and Wages Payable $800
Unearned Service Revenue 750
Supplies Expense 950
Insurance Expense 400
Salaries and Wages Expense 2,900
Service Revenue 2,000

a. If the amount in Supplies Expense is the January 31 adjusting entry, and $1,000 of supplies was purchased in January, what was the balance in Supplies on January 1?
b. If the amount in Insurance Expense is the January 31 adjusting entry, and the original insurance premium was for one year, what was the total premium and when was the policy purchased?
c. If $3,500 of salaries was paid in January, what was the balance in Salaries and Wages Payable on December 31, 2014?