Final answer:
To subtract 43 - 21, subtract each place value starting from the rightmost digit to get 22.
Step-by-step explanation:
To subtract 43 - 21, you can line up the numbers vertically and subtract each place value. Starting from the rightmost digit, subtract 1 from 3 which gives you 2. Then, subtract 2 from 4 which gives you 2. Therefore, the answer is 22.
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