The cost of producing a product in a machinery factory was 168 yuan last year, and this year it has dropped by 20% compared to last year. How much does this product cost this year?
某机械厂生产一种产品的成本，去年是168元，今年比去年下降了20%．今年这种产品的成本是多少元？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">168 * (4/5)</gadget>
<output>672/5 = around 134.4</output>

<result>672/5 = around 134.4</result>