Work = (force) x (distance)
-- Floor portion:
Force = 12 N
Distance = 7.0 m
Work = (12 x 7) = 21 joules
-- Lift portion:
Weight of the box = (mass) x (gravity) = (3.0) x (9.8) = 29.4 newtons
Force to lift = weight of box = 29.4 N
Distance = 1 m
Work = (29.4 x 1) = 29.4 joules
Total work on the box = (21 + 29.4) = 50.4 joules