Three trapezoids A, B, C, the ratio of their heights is 1:2:3, the ratio of the lower base is 12:15:10, and the ratio of the upper base is 6:9:4, the known area of trapezoid A is 60 square centimeters, find the sum of the areas of the two trapezoids B and C.
三个梯形A，B，C，它们的高的比是1：2：3，下底之比是12：15：10，上底之比是6：9：4，已知梯形A的面积是60平方厘米，求B、C两个梯形的面积之和．
<gadget id="calculator">6 + 12</gadget>
<output>18</output>

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

<gadget id="calculator">18 * (1/2)</gadget>
<output>9</output>

<gadget id="calculator">9 + 15</gadget>
<output>24</output>

<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">24 * 1</gadget>
<output>24</output>

<gadget id="calculator">4 + 10</gadget>
<output>14</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">14 * (3/2)</gadget>
<output>21</output>

<gadget id="calculator">24 + 21</gadget>
<output>45</output>

<gadget id="calculator">45 / 9</gadget>
<output>5</output>

<gadget id="calculator">60 * 5</gadget>
<output>300</output>

<result>300</result>