I need help with this accounting question. Please show all work, thank you!

Oliveras Company had net credit sales during the year of $$800,000$ and cost of goods sold of $$500,000.$ The balance in accounts receivable at the beginning of the year was $$100,000,$ and the end of the year it was $$150,000.$ What were the accounts receivable turnover and the average collection period in days?

a$.7\mathrm{.}3$ and $64$ days.

b$.4\mathrm{.}0$ and $91\mathrm{.}3$ days.

c$.6\mathrm{.}4$ and $57$ days.

d$.8\mathrm{.}0$ and $45\mathrm{.}6$ days.