Tractor wheels

The tractor's front wheel has a circumference of 18 dm and the rear 60 dm. We will make a red mark on the lowest point of both wheels. The tractor then starts. At what distance from the start will both marks appear identically at the bottom again?

Correct answer:

x =  18 m

Step-by-step explanation:

$$\begin{gathered} a=18\text{dm} \\ b=60\text{dm} \\ 18=2\cdot 3^2 \\ 60=2^2\cdot 3\cdot 5 \\ LCM(18,60)=2^2\cdot 3^2\cdot 5=180 \\ c=LCM(a,b)=LCM(18,60)=180\text{dm} \\ x=c\to \text{m}=c:10\text{m}=180:10\text{m}=18\text{m}=18\text{m} \end{gathered}$$

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