Answer: 50,000.
Explanation: In the general rules of rounding numbers, we have that if the number we want to round, is followed by a 5, 6, 7, 8, or 9, we round the number up, and if it is followed by 0, 1, 2, 3, or 4, we round the number down, in this case we need to round the number 45,122 to the nearest ten thousand, which means that we need to round the first number (4, which represents the ten thousand position), as the number 4 is followed by a 5, we round the number up so the result is 50,000.