Known a: b=0.4: (1/4) When a is what, b=15.
已知a：b=0.4：(1/4)当a是多少时，b=15．
<gadget id="calculator">15 * 0.4</gadget>
<output>6</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">6 / (1/4)</gadget>
<output>24</output>

<result>24</result>