The sum of the numerator and denominator of a fraction is 120. If 45 is added to the numerator and 21 is subtracted from the denominator, the new fraction is divided into (4/5). What is the original fraction?
一个分数的分子和分母的和是120，如果分子加上45，分母减去21，新分数约分后是(4/5)，原来的分数是多少．
<gadget id="calculator">45 - 21</gadget>
<output>24</output>

<gadget id="calculator">120 + 24</gadget>
<output>144</output>

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

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">144 * (4/9)</gadget>
<output>64</output>

<gadget id="calculator">64 - 45</gadget>
<output>19</output>

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

<gadget id="calculator">144 * (5/9)</gadget>
<output>80</output>

<gadget id="calculator">80 + 21</gadget>
<output>101</output>

<gadget id="calculator">19 / 101</gadget>
<output>19/101 = around 0.188119</output>

<result>19/101 = around 0.188119</result>