In a subtraction formula, the sum of the minuend, the subtrahend and the difference is 180. It is known that the subtrahend is the minuend (5/9), what is the difference.
在一道减法算式中，被减数、减数与差的和是180，已知减数是被减数的(5/9)，差是多少．
<gadget id="calculator">180 / 2</gadget>
<output>90</output>

<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">90 * (5/9)</gadget>
<output>50</output>

<gadget id="calculator">90 - 50</gadget>
<output>40</output>

<result>40</result>