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South African Mathematics Olympiad

Algebra Difficulty 3.9 AMC 10/12 Find the answer South Africa

The number of different positive integers such that $\frac{n}{n+4} < \frac{4}{9}$ is

Pick one

Solution

Multiplying gives us $9n < 4n + 16$ , i.e. $5n < 16$ , so $n = 1$ or $2$ or $3$ .

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