There are 18 black and white balls of the same size in the bag, among which (5/6) are white balls, how many white balls are there? Black balls account for ((())/(())) of the total.
袋子里有18个大小相同的黑白两种球，其中(5/6)是白球，白球有多少个．黑球占总数的((())/(()))．
<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">18 * (5/6)</gadget>
<output>15</output>

<result>15</result>