Answer:
C. 35
Explanation:
Let x represent the largest of the multiples of 7. The sum will be ...
x + (x -7) + (x -14) = 84
3x = 105 . . . . . . . . . . . . . add 21 and simplify
x = 35 . . . . . . . . . . . . . . . divide by 3
The greatest of the numbers of interest is 35.
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Two consecutive multiples of 7 will differ by 7. If x is the largest, the next-largest is x-7, and the one before that is x-14.