When the sum of minuend, subtrahend and difference is 90, the ratio of difference to subtrahend is 5:4, what is the difference?
当被减数、减数、差的总和是90时，差与减数的比是5：4，则差是多少．
<gadget id="calculator">90 / 2</gadget>
<output>45</output>

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

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

<gadget id="calculator">45 * (5/9)</gadget>
<output>25</output>

<result>25</result>