Final answer:
Without the specifics of 'exhibit a', which should include information like average accounts receivable and total credit sales, it is not possible to calculate or determine the firm's days sales outstanding (DSO).
Step-by-step explanation:
The student's question about the firm's 'days sales outstanding' (DSO) essentially asks for the calculation of how many days on average it takes for a company to collect payment after making a sale, based on the provided exhibit information. Typically, to calculate DSO, one would use the formula: (average accounts receivable / total credit sales) × number of days. However, the exhibit a referenced in the question is not provided, making it impossible to calculate the DSO or to answer the question accurately. Therefore, without the specifics of 'exhibit a', like the average accounts receivable or the total credit sales, we cannot perform a calculation.