In December, General Motors produced $7,500$ customized vans at its plant in Detroit. The labor productivity at this plant is known to have been $0\mathrm{.}14$ vans per labor hour during that month. $320$ laborers were employed at the plant that month.

a$)$ In the month of December the average number of hours worked per laborer $=$ hours$/$laborer $($round your response to one decimal place$).$

b$)$ If productivity can be increased to $0\mathrm{.}15$ vans per hour, the average number of hours worked per laborer $=$ hours$/$laborer $($round your response to one decimal place$).$