Mr. Li plans to buy a house. If he pays in installments, there are two payment methods: one is to pay 175,000 yuan in the first year, and 25,000 yuan a year thereafter; the other payment method is to pay half the time in advance 4 years RMB 10,000, and pay 30,000 RMB per year for the second half of the time. The total amount and the payment period of these two payment methods are the same, so how much is Mr. Li’s total payment to buy this house?
李先生打算购买一套住房，如果分期付款，有两种付款方式：一种是开始第一年先付17.5万元，以后每年付款2.5万元；另一种付款方式是提前一半时间每年付款4万元，后一半时间每年付款3万元．这两种付款方式的总额和付款年限都相同，那么，李先生购买这套住房共需付款多少元？
<gadget id="calculator">17.5 - 2.5</gadget>
<output>15</output>

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

<gadget id="calculator">(1/2) * 4</gadget>
<output>2</output>

<gadget id="calculator">(1/2) * 3</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(3/2) - 2.5</gadget>
<output>-1</output>

<gadget id="calculator">2 + (-1)</gadget>
<output>1</output>

<gadget id="calculator">15 / 1</gadget>
<output>15</output>

<gadget id="calculator">15 - 1</gadget>
<output>14</output>

<gadget id="calculator">14 * 2.5</gadget>
<output>35</output>

<gadget id="calculator">17.5 + 35</gadget>
<output>52.5</output>

<result>52.5</result>