Hockey stadium fans

At the hockey match, the stadium was full at the beginning. After the first period, 20% of the fans left; after the second period, one-sixth of the remaining fans left. How many fans were in the stadium at the start of the match if 700 stayed until the end?

Final Answer:

n =  1050

Step-by-step explanation:

$$\begin{gathered} r=100\%-20\%=1-\frac{20}{100}=0.8 \\ 0.20n+r\cdot n/6+700=n \\ 0.20n+0.8\cdot n/6+700=n \\ 0.20\cdot n+0.8\cdot n/6+700=n \\ 4n=4200 \\ n=\frac{4200}{4}=1050 \\ n=1050 \end{gathered}$$

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