Solution ratio: (7/4): x=(2/5): (5/8).
解比例：(7/4)：x=(2/5)：(5/8)．
<gadget id="calculator">7 / 4</gadget>
<output>7/4 = around 1.75</output>

<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(5/8) / (2/5)</gadget>
<output>25/16 = around 1.5625</output>

<gadget id="calculator">(7/4) * (25/16)</gadget>
<output>175/64 = around 2.734375</output>

<result>175/64 = around 2.734375</result>