One quarter of the sum of 5 consecutive natural numbers is 2.5 more than the middle number. What is the first number among these five consecutive natural numbers?
5个连续自然数的和的四分之一比中间的数多2.5，这五个连续自然数中的第一个数是多少．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) * 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2.5 - (1/4) - (1/2)</gadget>
<output>1.75</output>

<gadget id="calculator">(1/4) + (1/2) + 1.75</gadget>
<output>2.5</output>

<gadget id="calculator">(1/4) - 1</gadget>
<output>-3/4 = around -0.75</output>

<gadget id="calculator">(1/4) + (1/4) + (1/4) + (1/4) + (-3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2.5 / (1/4)</gadget>
<output>10</output>

<gadget id="calculator">10 - 2</gadget>
<output>8</output>

<result>8</result>