When x=how much, 2x-1 is equal to the smallest composite number.
当x=多少时，2x-1等于最小的合数．
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<result>5/2 = around 2.5</result>