There are 12 black balls and white balls in the box. The black balls and white balls are the same size. If you touch a ball randomly, the probability of getting a white ball is (1/4). How many white balls are there in the box?
盒子里有黑球和白球共12个，黑球和白球的大小相同，任意摸一个球，摸到白球的可能性是(1/4)，盒子里有多少个白球．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">12 * (1/4)</gadget>
<output>3</output>

<result>3</result>