2.5 times of a number is 1 more than 5 times of 1.8, what is this number (column equation solution)
一个数的2.5倍比1.8的5倍多1，这个数是多少(列方程解)
<gadget id="calculator">1.8 * 5</gadget>
<output>9</output>

<gadget id="calculator">1 + 9</gadget>
<output>10</output>

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

<result>4</result>