(3/5) of a number is 1.8 less than (2/3) of 18, find this number. (solution by equation)
一个数的(3/5)比18的(2/3)少1.8，求这个数．(用方程解)
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">18 * (2/3)</gadget>
<output>12</output>

<gadget id="calculator">12 - 1.8</gadget>
<output>10.2</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">10.2 / (3/5)</gadget>
<output>17</output>

<result>17</result>