The perimeter of a rectangle is 30 decimeters, the known width is long (1/4), what is the width of this rectangle in decimeters?
一个长方形的周长是30分米，已知宽是长的(1/4)，这个长方形的宽是多少分米．
<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">4 / 1</gadget>
<output>4</output>

<gadget id="calculator">1 + 4</gadget>
<output>5</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">15 * (1/5)</gadget>
<output>3</output>

<result>3</result>