manuscript has 4,500 words, and it takes 50 minutes for A to type alone, and 75 minutes for B to type alone. Now that the two are working together, how many minutes will it take to print this manuscript?
一份稿件有4500字，甲单独打要50分钟完成，乙单独打要75分钟，现在两人合作，多少分钟能打印完这份稿件？
<gadget id="calculator">1 / 50</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">1 / 75</gadget>
<output>1/75 = around 0.013333</output>

<gadget id="calculator">(1/50) + (1/75)</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">1 / (1/30)</gadget>
<output>30</output>

<result>30</result>