Final answer:
To estimate a 20% tip on a dinner bill of $159.75, round the bill amount to the nearest ten dollars and then calculate 20% of the rounded value.
Step-by-step explanation:
To estimate a 20% tip on a dinner bill of $159.75, first round the bill amount to the nearest ten dollars. The nearest ten dollars is $160. Now, calculate 20% of $160 by multiplying it with 0.2.
20% of $160 = $160 * 0.2 = $32.
Therefore, a 20% tip on a dinner bill of $159.75, rounded to the nearest ten dollars, is $32.
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