The base of a triangle is 15cm, and the height is 2/5 of the base. What is the area of the triangle?
一个三角形的底是15cm，高是底的(2/5)，这个三角形的面积是多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">15 * (2/5)</gadget>
<output>6</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">15 * 3</gadget>
<output>45</output>

<result>45</result>