The original price of a set of tables and chairs is 180 yuan, how much is it cheaper after the 20% discount?
一套桌椅原价180元，打八折后便宜多少元？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">180 * (4/5)</gadget>
<output>144</output>

<gadget id="calculator">180 - 144</gadget>
<output>36</output>

<result>36</result>