Final answer:
To estimate the difference between 109 and 71 by rounding to the nearest ten, we round both numbers to the nearest ten and subtract. The difference is 40.
Step-by-step explanation:
To estimate the difference between 109 and 71 by rounding to the nearest ten, we round both numbers to the nearest ten and then subtract. Rounding 109 to the nearest ten gives us 110, and rounding 71 to the nearest ten gives us 70. Subtracting 70 from 110 gives us a difference of 40.
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