The ratio of the number of teeth of the large and small gears is 5:3, the small gear has 15 teeth, how many teeth does the large gear have.
大小齿轮齿数的比是5：3，小齿轮有15个齿，大齿轮有多少个齿．
<gadget id="calculator">15 / 3</gadget>
<output>5</output>

<gadget id="calculator">5 * 5</gadget>
<output>25</output>

<result>25</result>