Final answer:
The firm collected $1,320 in the month of March.
Step-by-step explanation:
To determine the amount the firm collected in the month of March, we need to calculate the receivables balance at the end of March. The accounts receivable period is 60 days, so the receivables balance at the end of March would include sales from January and February.
Adding up the sales for January through February, we get $350 + $380 = $730.
Since the beginning receivables balance on January 1st was $590, the receivables balance at the end of March would be $590 + $730 = $1,320. Therefore, the firm collected $1,320 in the month of March.