Teacher Zhu went to Guoguang Supermarket and bought a suit with a 15% discount for 680 yuan, which is how much more than before the discount.
朱老师到国光超市买了件打八五折的西装680元，比打折前优惠了多少元．
<gadget id="calculator">85 / 100</gadget>
<output>17/20 = around 0.85</output>

<gadget id="calculator">680 / (17/20)</gadget>
<output>800</output>

<gadget id="calculator">800 - 680</gadget>
<output>120</output>

<result>120</result>