Besides the city of Rome, what were two cities in the Roman Empire where trade by sea likely occurred?

Goods were not only exchanged across the Roman world, however, as bustling ports such as Gades, Ostia, Puteoli, Alexandria, and Antioch also imported goods from such far-flung places as Arabia, India, Southeast Asia, and China.

Explanation:

the correct answer is:   "   3.6 % " .

          →   the unemployment rate is:   " 3.6 % " .

explanation:

to calculate the "unemployment rate" :

the "unemployment rate"   =

  [# of people unemployed] /   [working age population]   * 100 %   ;

                =   [9 million] / [250 million]     *   100 % ;

    →     note:   the units of "million" cancel out;

                    since:   " {million} / {million} = 1 " ;

                =   (9 / 250)   * 100 %   ;

                = 0.036 * 100 % ;

                =   3.6 %

answer:   the unemployment rate is:   " 3.6 % " .