The school plans to purchase a batch of tables and chairs, and the ratio of the number of tables to chairs is 3:5. In the actual purchase, the planned 20 chairs were changed to purchase tables. As a result, the number of tables was 20% less than the number of chairs. How many tables were originally planned to be purchased?
学校计划购置一批桌椅，桌子与椅子数量的比是3：5．实际购买时把计划中的20把椅子改为了购买桌子，结果桌子的数量比椅子少20%，原计划购买桌子多少张．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">20 * (1/5)</gadget>
<output>4</output>

<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<gadget id="calculator">20 + 16</gadget>
<output>36</output>

<gadget id="calculator">5 / 3</gadget>
<output>5/3 = around 1.666667</output>

<gadget id="calculator">(5/3) * (1/5)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(5/3) - (1/3) - 1</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">36 / (1/3)</gadget>
<output>108</output>

<result>108</result>