Answer:
40
Step-by-step explanation:
Any solution x will mod 23 will also have x+23n as a solution, for some integer n. Since 900/23 = 39 3/23, we know there are 39 or 40 three-digit integers of this form.
As it happens, 100 is the smallest 3-digit solution. So, there are 40 three-digit numbers that are of the form 100 +23n, hence 40 solutions to the equation.
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The equation reduces, mod 23, to ...
10x = 11
Its solutions are x = 23n +8.
