Solution ratio: 2x:7.2=5:4.
解比例：2x：7.2=5：4．
<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(5/4) * 7.2</gadget>
<output>9</output>

<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<result>9/2 = around 4.5</result>