Garden - fence

The fence around the garden measures 360 m. Of these, 72 18/20 m are damaged and must be repaired. How many meters of fence is sufficient?

Correct answer:

x =  287 ¹⁄₁₀ = 2871/10 m

Step-by-step explanation:

$$\begin{gathered} a=360\text{m} \\ b=72\frac{18}{20}=72+\frac{18}{20}=\frac{72\cdot 20+18}{20}=\frac{1440+18}{20}=\frac{1458}{20}=\frac{729}{10}=72.9\text{m} \\ x=a-b=360-\frac{729}{10}=\frac{360\cdot 10}{10}-\frac{729}{10}=\frac{3600}{10}-\frac{729}{10}=\frac{3600-729}{10}=\frac{2871}{10}=\frac{2871}{10}\text{m}=287\frac{1}{10}\text{m}=287.1\text{m} \end{gathered}$$

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