A shopping mall has a discount promotion. A one-time consumption of 100 yuan or more can enjoy a 10% discount, a 20% discount for those who spend more than 100 yuan, and a 50% discount for those who spend more than 200 yuan. Mr. Zhang spent a total of 420 yuan. The actual value of what Mr. Zhang bought What is the price?
某商场进行打折促销，一次性消费满100元可享9折优惠，超过100元部分享8折优惠，超过200元部分享5折优惠，张先生共消费420元，张先生所买东西的实际价格是多少钱？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">100 * (9/10)</gadget>
<output>90</output>

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

<gadget id="calculator">100 * (4/5)</gadget>
<output>80</output>

<gadget id="calculator">420 - 100 - 100</gadget>
<output>220</output>

<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">220 * (1/2)</gadget>
<output>110</output>

<gadget id="calculator">90 + 80 + 110</gadget>
<output>280</output>

<result>280</result>