After combining two cylinders of the same shape and size into a large cylinder with a height of 18 cm, the surface area is reduced by 30 cm2. What is the volume of each cylinder in cubic centimeters?
把两个形状、大小一样的圆柱拼成一个高18厘米的大圆柱后，表面积减少30平方厘米．原来每个圆柱的体积是多少立方厘米．
<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<gadget id="calculator">15 * 9</gadget>
<output>135</output>

<result>135</result>