Pour 30 liters of water into a cuboid fish tank with a length of 5 decimeters, a width of 3 decimeters, and a height of 5 decimeters. How many decimeters are there between the water surface and the mouth of the tank?
把30升水倒入一个长5分米、宽3分米、高5分米的长方体鱼缸中，水面距缸口还有多少分米．
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">30 / 15</gadget>
<output>2</output>

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

<result>3</result>