A pile of coal has a total of 90 tons. (2/15) of this pile of coal has been used up. How many tons of coal have been used?
一堆煤共90吨，已经用去了这堆煤的(2/15)，用去了多少吨煤？
<gadget id="calculator">2 / 15</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">90 * (2/15)</gadget>
<output>12</output>

<result>12</result>