If the numerator of the fraction ((b)/2) is reduced by 4.5 times, the fraction is equal to 5, then b=how much.
如果把分数((b)/2)的分子缩小4.5倍后这个分数就等于5，那么b=多少．
<gadget id="calculator">4.5 * 5</gadget>
<output>22.5</output>

<gadget id="calculator">22.5 * 2</gadget>
<output>45</output>

<result>45</result>