A bit vague since it's not clear whether the applied force is in the same direction as the box's displacement. But let's assume it is. Then the work done is:
W = Fd
W = work, F = force, d = displacement
Given values:
F = 10.0N, d = 0.9m
Plug in and solve for W:
W = 10.0(0.9)
W = 9J
