The perimeter of a rectangle is x, and the length is three times the width, what is the formula for finding the width?
一个长方形的周长是x，长是宽的3倍，求宽列式是多少．
<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>