A school replaces a batch of desks and chairs with special funds for maintenance. If you only buy desks for these funds, you can buy exactly 240 desks; if you only buy school chairs, you can buy exactly 400 sets. Then, how many sets of desks and chairs can you buy with this special fund ( a table and a chair).
某校用维修专款更换一批课桌椅，这些款若只买课桌恰好可以买240张；若只买课椅恰好可以买400把，那么，用这批专款可以买多少套课桌椅(一张桌子一把椅子)．
<gadget id="calculator">1 / 240</gadget>
<output>1/240 = around 0.004167</output>

<gadget id="calculator">1 / 400</gadget>
<output>1/400 = around 0.0025</output>

<gadget id="calculator">(1/240) + (1/400)</gadget>
<output>1/150 = around 0.006667</output>

<gadget id="calculator">1 / (1/150)</gadget>
<output>150</output>

<result>150</result>