The classroom

The classroom is 9 meters long. Its width is smaller and can be passed in equally long steps of 55 CM or 70 CM. Find the width of the classroom.

Correct answer:

b =  7.7 m

Step-by-step explanation:

$$\begin{gathered} a=9\text{m} \\ 55=5\cdot 11 \\ 70=2\cdot 5\cdot 7 \\ LCM(55,70)=2\cdot 5\cdot 7\cdot 11=770 \\ x=LCM(55,70)=770\text{cm} \\ b<a \\ b=x\to \text{m}=x:100\text{m}=770:100\text{m}=7.7\text{m}=7.7\text{m} \end{gathered}$$

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