Put two cubes together to form a cuboid. The surface area of this cuboid is 90 square decimeters. What is the surface area of a cube?
把两个正方体拼成一个长方体，这个长方体的表面积是90平方分米，一个正方体的表面积是多少．
<gadget id="calculator">12 - 2</gadget>
<output>10</output>

<gadget id="calculator">90 / 10</gadget>
<output>9</output>

<gadget id="calculator">9 * 6</gadget>
<output>54</output>

<result>54</result>