In a subtraction formula, the sum of the minuend, the subtrahend and the difference is 72, and the ratio of the subtrahend to the difference is 4:5. What is the subtrahend?
在一个减法算式中，被减数、减数、差三个数相加的和是72，减数和差的比是4：5，减数是多少．
<gadget id="calculator">72 / 2</gadget>
<output>36</output>

<gadget id="calculator">4 + 5</gadget>
<output>9</output>

<gadget id="calculator">36 / 9</gadget>
<output>4</output>

<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<result>16</result>