9514 1404 393
Answer:
x = 6
Explanation:
The place values of the digits from left to right are b^2, b, 1.
The units digits have a sum of 9, but that is represented in these numbers by a units digit of 3 and a "b" digit of 1.
9 will be represented by b +3 when b = 6
The base of these numbers is 6.
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Additional comment
Translated to decimal, the sum is 207 = 100 + 107.