The unadjusted trial balance shows the following accounts with zero or normal balances on 12/31/2021 Rent Expense 3.600 Supplies 1,300 Note Receivable 10,000 Interest receivable 0 - Rent Expense 0 Supplies Expense 0 . Accounts Receivable 900 If Accounts Receivable were $1,200 as of 1/1/2021, and cash collections were $51,000 during the year, how much were credit sales (all sales were on credit)