in our primary disbursement accounts which were reclassified as accounts payable and other accrued liabilities on our consolidated balance sheet . concentration of credit risk financial instruments that potentially subject us to concentrations of credit risk consist of cash and cash equivalents , trade accounts receivable and derivative instruments . we place our cash and cash equivalents with high quality financial institutions . such balances may be in excess of fdic insured limits . in order to manage the related credit exposure , we continually monitor the credit worthiness of the financial institutions where we have deposits . concentrations of credit risk with respect to trade accounts receivable are limited due to the wide variety of customers and markets in which we provide services , as well as the dispersion of our operations across many geographic areas . we provide services to commercial , industrial , municipal and residential customers in the united states and puerto rico . we perform ongoing credit evaluations of our customers , but do not require collateral to support customer receivables . we establish an allowance for doubtful accounts based on various factors including the credit risk of specific customers , age of receivables outstanding , historical trends , economic conditions and other information . no customer exceeded 5% ( 5 % ) of our outstanding accounts receivable balance at december 31 , 2009 or 2008 . accounts receivable , net of allowance for doubtful accounts accounts receivable represent receivables from customers for collection , transfer , recycling , disposal and other services . our receivables are recorded when billed or when the related revenue is earned , if earlier , and represent claims against third parties that will be settled in cash . the carrying value of our receivables , net of the allowance for doubtful accounts , represents their estimated net realizable value . provisions for doubtful accounts are evaluated on a monthly basis and are recorded based on our historical collection experience , the age of the receivables , specific customer information and economic conditions . we also review outstanding balances on an account-specific basis . in general , reserves are provided for accounts receivable in excess of ninety days old . past due receivable balances are written-off when our collection efforts have been unsuccess- ful in collecting amounts due . the following table reflects the activity in our allowance for doubtful accounts for the years ended december 31 , 2009 , 2008 and 2007: .

2009: balance at beginning of year: 65.7
additions charged to expense: 27.3
accounts written-off: -37.8
acquisitions: -
balance at end of year: 55.2
2008: balance at beginning of year: 14.7
additions charged to expense: 36.5
accounts written-off: -12.7
acquisitions: 27.2
balance at end of year: 65.7
2007: balance at beginning of year: 18.8
additions charged to expense: 3.9
accounts written-off: -7.8
acquisitions: -0.2
balance at end of year: 14.7

subsequent to our acquisition of allied , we recorded a provision for doubtful accounts of $ 14.2 million to adjust the allowance acquired from allied to conform to republic 2019s accounting policies . we also recorded $ 5.4 million to provide for specific bankruptcy exposures in 2008 . in 2007 , we recorded a $ 4.3 million reduction in our allowance for doubtful accounts as a result of refining our estimate of the allowance based on our historical collection experience . restricted cash as of december 31 , 2009 , we had $ 236.6 million of restricted cash , of which $ 93.1 million was proceeds from the issuance of tax-exempt bonds and other tax-exempt financings and will be used to fund capital republic services , inc . and subsidiaries notes to consolidated financial statements , continued .

Questions:
during 2009, what was the total of additions charged to expense?
and what was the total of accounts written-off?
what was, then, the combined total of both segments?
and as of december 31 of that year, what percentage of the restricted cash was due to proceeds from the issuance of tax-exempt bonds?

Answers:
27.3
-37.8
-10.5
39.3%