A fraction is (9/6), if 4 is added to the denominator, how much should be added to the numerator to keep the size of the fraction constant?
一个分数是(9/6)，若分母加4，为使分数的大小不变，分子应该加上几？
<gadget id="calculator">5 / 3</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">9 * (5/3)</gadget>
<output>15</output>

<gadget id="calculator">15 - 9</gadget>
<output>6</output>

<result>6</result>