Given the line segment AB=18cm, M is the midpoint of AB, C is a point on AB, and AC=5BC, find the length of MC.
已知线段AB=18cm，M是AB的中点，C是AB上一点，且AC=5BC，求MC的长．
<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">(5/6) * 18</gadget>
<output>15</output>

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

<gadget id="calculator">15 - 9</gadget>
<output>6</output>

<result>6</result>