There is a batch of materials to be copied, which can be completed in 11 hours by machine A alone or by machine B in 13 hours. When both machines A and B make copies at the same time, due to mutual interference, the two machines print less than 28 sheets per hour. Now it took 6 hours and 15 minutes for the two machines to copy at the same time. How many sheets are there in this batch of data?
有一批资料要复印，甲机独印11小时或乙机独印13小时可完成，当甲、乙机同时复印，因相互干扰，每小时两台共少印28张．现在两机同时复印用了6小时15分钟印完．则这批资料共有多少张．
<gadget id="calculator">1 / 11</gadget>
<output>1/11 = around 0.090909</output>

<gadget id="calculator">1 / 13</gadget>
<output>1/13 = around 0.076923</output>

<gadget id="calculator">25 / 4</gadget>
<output>25/4 = around 6.25</output>

<gadget id="calculator">1 / (25/4)</gadget>
<output>4/25 = around 0.16</output>

<gadget id="calculator">(1/13) - (4/25)</gadget>
<output>-27/325 = around -0.083077</output>

<gadget id="calculator">(1/11) + (-27/325)</gadget>
<output>28/3_575 = around 0.007832</output>

<gadget id="calculator">28 / (28/3_575)</gadget>
<output>3_575</output>

<result>3_575</result>