Cash Flows from $($Used for$)$ Operating Activities$-$Direct Method

The cash flows from $($used for$)$ operating activities are reported by the direct method on the statement of cash flows. Determine the following:

a$.$ If sales for the current year were $$509,400$ and accounts receivable decreased by $$35,100$ during the year, what was the amount of cash received from customers?

b$.$ If income tax expense for the current year was $$50,400$ and income tax payable decreased by $$6,500$ during the year, what was the amount of cash paid for income taxes?

c$.$ Briefly explain why the cash received from customers in part $($a$)$ is different from sales.

Because the customers paid

$$ than the amount of sales for the period, cash received from customers

$$ sales made on account by $$35,100$ during the current year.