The perimeter of a right-angled trapezoid is 105 cm, the ratio of the sum of the two bases to the sum of the two waists is 3:2, and one of the waists is as long as the other (2/5), what is the area of this right-angled trapezoid ?
一个直角梯形的周长是105厘米，两底之和与两腰之和的比是3：2，且其中一腰长是另一腰长的(2/5)，这个直角梯形的面积是多少？
<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">105 * (3/5)</gadget>
<output>63</output>

<gadget id="calculator">105 - 63</gadget>
<output>42</output>

<gadget id="calculator">2 + 5</gadget>
<output>7</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">42 * (2/7)</gadget>
<output>12</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">63 * 6</gadget>
<output>378</output>

<result>378</result>