Explanation:
Here's how we can calculate the total amount they paid:
Start with the original bill: $68.89
Subtract the coupon: $68.89 - $10 = $58.89
Calculate the tip: $58.89 * 15% = $8.83 (Note: To calculate the tip, we multiply the subtotal by the percentage as a decimal. 15% is equivalent to 0.15 as a decimal)
Add the tip to the subtotal: $58.89 + $8.83 = $67.72
Therefore, Greg and Alana paid a total of $67.72 for their dinner.