shopping mall is launching promotions for the Double Festival. No discount will be given for purchases of less than 200 yuan, and 10% discount for purchases exceeding 200 yuan and no more than 500 yuan on New Year’s Day. The two purchases cost 180 yuan and 405 yuan respectively. If the person combines the two purchases, how much will he spend less on one purchase?
某商场迎双节进行促销，购物不超过200元不给优惠，超过200元旦不超过500元的优惠10%，超过500元，其中500元按9折优惠，超过部分按8折优惠，某人两次购物分别用了180元，405元，若此人将两次的钱合起来，一次购物会少花多少钱？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">500 * (9/10)</gadget>
<output>450</output>

<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">405 / (9/10)</gadget>
<output>450</output>

<gadget id="calculator">180 + 450</gadget>
<output>630</output>

<gadget id="calculator">630 - 500</gadget>
<output>130</output>

<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">130 * (4/5)</gadget>
<output>104</output>

<gadget id="calculator">450 + 104</gadget>
<output>554</output>

<gadget id="calculator">405 - 554</gadget>
<output>-149</output>

<gadget id="calculator">180 + (-149)</gadget>
<output>31</output>

<result>31</result>