It is known that the ratio of A to B is 2:7, the sum of A and B is 36, how much less is A than B
已知甲数与乙数的比是2：7，甲乙两数的和是36，甲数比乙数少多少
<gadget id="calculator">2 + 7</gadget>
<output>9</output>

<gadget id="calculator">7 / 9</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">(7/9) - (2/9)</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">36 * (5/9)</gadget>
<output>20</output>

<result>20</result>