35% of a number minus 2.8 equals 3.5, find this number.
一个数的35%减去2.8等于3.5，求这个数．
<gadget id="calculator">2.8 + 3.5</gadget>
<output>6.3</output>

<gadget id="calculator">35 / 100</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">6.3 / (7/20)</gadget>
<output>18</output>

<result>18</result>