There is a group of donations to buy desks and chairs for a certain elementary school. If you only buy desks, you can buy 100 sets. If you only buy chairs, you can buy 300 sets. How many sets of desks and chairs can you buy with the money.
有一批捐款，给某小学买课桌椅，如果只买桌子可买100张，如果只买椅子可买300把，用这些钱可买多少套课桌椅．
<gadget id="calculator">1 / 100</gadget>
<output>1/100 = around 0.01</output>

<gadget id="calculator">1 / 300</gadget>
<output>1/300 = around 0.003333</output>

<gadget id="calculator">(1/100) + (1/300)</gadget>
<output>1/75 = around 0.013333</output>

<gadget id="calculator">1 / (1/75)</gadget>
<output>75</output>

<result>75</result>