It takes 10 hours to type a manuscript, and 8 hours for B. After 4 hours of typing together, there are still 5,000 words left. How many words are in this manuscript?
打一份稿件甲需要10小时，乙需要8小时，两人合打了4个小时后还剩下5000字，这份稿件有多少字？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/10) + (1/8)</gadget>
<output>9/40 = around 0.225</output>

<gadget id="calculator">(9/40) * 4</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 - (9/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">5_000 / (1/10)</gadget>
<output>50_000</output>

<result>50_000</result>