How do we compute Common-size percents for the company? If the company has cash and equivalents $108.6, accounts receivable $1674.4, Inventories $ 1396.9, Retained earnings $3043.4, Cost of sales 6,065.5, Income taxes $253.4, Revenues 9,553.1, and total assets 5,397.4.

usually you need a complete B/S or Y/S data to calculate common size percentages.
E.g.
In Y/S(Income Statement) Common size ratio is percentage of each variable in Y/S to Revenue. For example: COGS/Revenue, Gross Profit/Revenue, etc