The adjusted trial balances of ACF, Inc., at July 31, 2018, and July 31, 2019, include these amounts: 2018 2019 Supplies. . . . . . . . . . . . . . . . . . . . . $1,200 $3,400 Salaries payable. . . . . . . . . . . . . . 800 4,500 Unearned service revenue. . . . . . 11,000 9,900 Analysis of the accounts at July 31, 2019, reveals these transactions for the past 12 months: Purchases of supplies. . . . . . . . . . . . . . . . . . . . . . . $9,100 Cash payments for salaries. . . . . . . . . . . . . . . . . . . 55,500 Cash receipts in advance for service revenue. . . . 72,000 Begin by completing the Supplies T-account to solve for supplies expense for the year