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South African Mathematics Olympiad

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

If $a \bullet b$ means the value of $ab + a + b$ , and $5 \bullet x = 35$ , the value of $x$ must be

Pick one

Solution

By definition of $\bullet$ , we know $5 \bullet x = 5x + 5 + x = 6x + 5$ . If this is $35$ , then $6x = 30$ , so $x = 5$

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