A job can be done in 63 days first, and then B alone can complete it in 28 days; if two people cooperate to complete the job in 48 days, if A does the job alone, how many days will it take to complete the job?
一项工作甲先做63天，再由乙独做28天可以完成；如果两人合作48天可以完成，如果由甲单独做这项工作，需几天完成这项工作？
<gadget id="calculator">1 / 48</gadget>
<output>1/48 = around 0.020833</output>

<gadget id="calculator">(1/48) * 28</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">1 - (7/12)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">63 - 28</gadget>
<output>35</output>

<gadget id="calculator">(5/12) / 35</gadget>
<output>1/84 = around 0.011905</output>

<gadget id="calculator">1 / (1/84)</gadget>
<output>84</output>

<result>84</result>