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Algebra Difficulty 2.2 Junior Find the answer

The average of 1, 3, and x x is 3. What is the value of x x ?

A number or a short expression. Spacing and $ signs are ignored.

Solution

Since the average of three numbers equals 3, then their sum is 3×3=9 3 \times 3 = 9 . Therefore, 1+3+x=9 1+3+x=9 and so x=94=5 x=9-4=5 .

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