A flight attendant pulls her $70\mathrm{.}0$ N flight bag a distance of $253$ m along a level airport floor at a constant speed. The force she exerts is $40\mathrm{.}0$ N at an angle of $52\mathrm{.}0$ above the horizontal. Find the following:

$($a$)$ the work she does on the flight bag.

$($b$)$ the work done by the force of friction on the flight bag.

$($c$)$ the coefficient of friction between the flight bag and the floor.