Xiao Ming planted a sapling. At the beginning, the sapling was 55 cm high. After 9 weeks of planting, the sapling grew to 109 cm. How many centimeters does it grow per week on average? (solution by equation)
小明种了一株树苗，开始时树苗高55厘米，栽种9周后，树苗长高到109厘米，平均每周长高多少厘米？(用方程解)
<gadget id="calculator">109 - 55</gadget>
<output>54</output>

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

<result>6</result>