Which is cheaper for a $76 item that costs $10.25 to ship? A 15% coupon off the cost of the item or free shipping?

A 15% coupon is cheaper than free shipping.

This is because the coupon makes it $74.85 while free shipping is $76.

The coupon is $74.85 because 85% of 76 is $64.6 + shipping making it 74.85.

A 15% discount on the $76 price would reduce it by

0.15*$76.00 = $11.40

This amount is greater than the shipping fee, so the coupon gives a better deal than free shipping.