Johanna Lucy makes wooden boxes in which to ship motorcycles. Lucy and her three employees invest a total of $40$ hours per day making the $120$ boxes.

a$)$ Their productivity $=$ boxes$/$hour$.($Round your response to two decimal places.$)$

Lucy and her employees have discussed redesigning the process to improve efficiency. Suppose they can increase the rate to $125$ boxes per day.

b$)$ Their new productivity $=$ boxes$/$hour$.($Round your response to two decimal places.$)$

c$)$ The unit increase in productivity is boxes$/$hour$.($Round your response to two decimal places.$)$

d$)$ The percentage increase in productivity is $\%.($Enter your response as a percentage rounded to two decimal places.$)$