A cuboid glass fish tank is 5 decimeters long, 3 decimeters wide, and 3.5 decimeters high, and the depth of water in the tank is 3 decimeters. How many square decimeters is the contact area between the water and the fish tank?
一个长方体玻璃鱼缸，长5分米，宽3分米，高3.5分米，鱼缸中水深3分米．则水与鱼缸的接触面积是多少平方分米？
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">3 * 3 * 2</gadget>
<output>18</output>

<gadget id="calculator">5 * 3 * 2</gadget>
<output>30</output>

<gadget id="calculator">15 + 18 + 30</gadget>
<output>63</output>

<result>63</result>