The amount John gets paid in a week = $312
Explanation:
John gets paid with two different rates
Payment for first 40 cars = ($6 per car)
Different rate for all other cars after those first 40 = ($6 per hour + 50% of $6)
= ($6 + $3) = ($9 per car)
Since he makes 48 cars,
He gets paid = ($6 x 40 cars)
= ($240) + 8 extra cars at $9 per car ($72)
The amount John gets paid in a week = $312