A 25.0 kg object is accelerated from rest through a distance of 6.0 m in 4.0 s across a level floor. If the force due to friction between the object and the floor is 3.8 N, what is the work done in moving the object?

is the work done on due to friction negative?

w=fdcos(180)

the total work is work due to force + work due to friction but because friction has a negative sign I subtracted them

but the solution says that work due to friction is positive, so you add them all up

but why?