A fraction, the sum of the numerator and the denominator is 80, the fraction is reduced to (2/3), what is the original fraction.
一个分数，分子与分母的和是80，这个分数约分后是(2/3)，原分数是多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">80 * (3/5)</gadget>
<output>48</output>

<gadget id="calculator">(2/5) / 48</gadget>
<output>1/120 = around 0.008333</output>

<gadget id="calculator">80 * (1/120)</gadget>
<output>2/3 = around 0.666667</output>

<result>2/3 = around 0.666667</result>