A hydraulic jack is designed so that when the handle is pushed down 1 m, the piston raising the load moves up 0.015 m.

IMA= 66.67
AMA= 26.67
Efficiency= 40%

At this efficiency, what is the force required to lift a 5000 N weight?

The ideal mechanical advantage is

1/0.015 = 66.67 They tell you that already.

Because of inefficiency (friction), you have to apply
1/26.67 times the lifted weight, or 187.5 N