There are three trapezoids A, B, and C. The ratio of their heights is 1:2:3; the ratio of the upper and lower bases is 6:9:4; the ratio of the lower bases is 12:15:10. Given that the area of trapezoid A is 30 square centimeters, what is the sum of the areas of trapezoids B and C?
有甲、乙、丙三个梯形，它们的高之比是1：2：3；上底之比依次是6：9：4；下底之比依次12：15：10．已知甲梯形的面积是30平方厘米，那么乙与丙两个梯形的面积之和是多少平方厘米？
<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">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">21 + 24</gadget>
<output>45</output>

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

<gadget id="calculator">30 * 5</gadget>
<output>150</output>

<result>150</result>