Uncle Wang participates in rural cooperative medical insurance in our county. The clause stipulates: a deductible line is set for farmers' hospitalization medical expenses, and the county-level medical institutions pay 400 yuan, and the part above the deductible line is compensated at 45%. Uncle Wang suffered from acute enteritis in April this year, and was hospitalized in a designated hospital for 20 days. The medical expenses totaled 8,280 yuan. According to the terms and conditions, how much does Uncle Wang only need to pay?
王大伯参加我县农村合作医疗保险．条款规定：农民住院医疗费设起付线，县级医疗机构为400元，在起付线以上的部分按45%补偿．今年4月份王大伯患了急性肠炎，在定点医院住院治疗了20天，医疗费用共计8280元，．按条款规定，王大伯只要自付多少元？
<gadget id="calculator">8_280 - 400</gadget>
<output>7_880</output>

<gadget id="calculator">45 / 100</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">1 - (9/20)</gadget>
<output>11/20 = around 0.55</output>

<gadget id="calculator">7_880 * (11/20)</gadget>
<output>4_334</output>

<gadget id="calculator">4_334 + 400</gadget>
<output>4_734</output>

<result>4_734</result>