Uncle Zhang is going to donate a sum of money to the school to buy desks and stools. If you use all the donations, you can buy 60 sets of tables and stools, if you only buy tables, you can buy 80 sets, if you only buy stools, how many sets can you buy.
张叔叔准备捐献一笔款给学校买课桌凳．若用全部捐款可买60套桌凳，若只买桌子，可买80张，若只买凳子，可买多少条．
<gadget id="calculator">1 / 60</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">1 / 80</gadget>
<output>1/80 = around 0.0125</output>

<gadget id="calculator">(1/60) - (1/80)</gadget>
<output>1/240 = around 0.004167</output>

<gadget id="calculator">1 / (1/240)</gadget>
<output>240</output>

<result>240</result>