Answer: an estimated 15% tip on a dinner bill of $58.12 would be $8.72.
Explanation:
First, we can calculate 10% of $58.12 by moving the decimal point one place to the left, which gives us $5.81.
Then, we can calculate half of 10%, which is 5%, by dividing $5.81 by 2, giving us $2.91.
Finally, we add 10% and 5% to get the estimated tip amount:
$5.81 + $2.91 = $8.72
Therefore, an estimated 15% tip on a dinner bill of $58.12 would be $8.72.