A rectangular container with a length and width of 10 cm is filled with water at a depth of 30 cm. Put a round steel with a base area of 40 cm2 vertically into the container so that the bottom surface touches. Now gently lift the round bar upwards. Lift 4 centimeters, how many centimeters is the round steel wetted by water at this time?
一个长和宽都是10厘米的长方形容器里装有30厘米深的水，把一根底面积是40平方厘米的圆钢垂直地放进容器里并使底面接触，现在轻轻地把圆钢向上提起4厘米，这时水面被水浸湿的圆钢有多少厘米．
<gadget id="calculator">100 - 40</gadget>
<output>60</output>

<gadget id="calculator">4 / 60</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">40 * (1/15)</gadget>
<output>8/3 = around 2.666667</output>

<gadget id="calculator">4 + (8/3)</gadget>
<output>20/3 = around 6.666667</output>

<result>20/3 = around 6.666667</result>