Holy and his associate, John, are university juniors and have started a part-time company. They focus on finding stylish products to sell while the products are a fad and then move on to finding the next product. They are currently selling Lens accessories which people use to take pictures of their surroundings. Holy orders parts from South Korea and he and John must unpack the parts, assemble the lenses, and then repack in a retail box. Since Holy and John are full-time juniors, they can dedicate 15 hours each to the assembly and packaging process per week. On average, they can assemble and box 400 Lens accessories per week from their combined effort.

A) What is the productivity per labor hour?

B) John learns about efficiency in his university course and organizes the assembly and packaging process differently. Now he and Holy can assemble 437 Lens accessories per week without increasing their hours. What is their percentage change in productivity per labor hour?