Inventory, Dec. 31 45,000
Inventory, Jan. 1 52,000
cash, Dec. 31 10,000
purchases during the yr 255,000
sales during the year 480,000

Compute CGS

CGS = Beg. Inv. + purchases - ending inv.

CGS = 52,000 + 255,000 - 45,000
CGS = 262,000

Did I compute CGS correctly?

Correct.