John will earn $127.72 for delivering $452 worth of pizza during a 6-hour shift. This is calculated by multiplying his base salary of $7.15 per hour by 6 hours, which equals $42.90, and then adding 18% of the price of the pizza, which is $452 x 0.18 = $81.36. Therefore, the total amount he will earn is $42.90 + $81.36 = $127.72.