Answer the following questions, assuming the year begins January 1. (a) If the amount in Supplies Expense is the January 31 adjusting entry, and $850 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 $2,500 of salaries was paid in January, what was the balance in Salaries and Wages Payable at December 31, 2019? (d) If $1,600 was received in January for services performed in January, what was the balance in Unearned Service Revenue at December 31, 2019?