The area of a trapezoid is 63 square centimeters, the height is 15 centimeters, and the upper base is 2.4 cm. What is the lower base of the trapezoid in centimeters?
一个梯形的面积是63平方厘米，高是15厘米，上底是2.4厘米，这个梯形的下底是多少厘米．
<gadget id="calculator">2 / 15</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">63 * (2/15)</gadget>
<output>42/5 = around 8.4</output>

<gadget id="calculator">(42/5) - 2.4</gadget>
<output>6</output>

<result>6</result>