Answer:
a) Force must be applied to the input piston = 10N
b) The input piston moved by 7.5 m
Step-by-step explanation:
a) For a hydraulic lift we have equation

F₁ = ?
d₁ = 10 cm = 0.1 m
F₂ = 250 N
d₂ = 50 cm = 0.5 m
Substituting

Force must be applied to the input piston = 10N
b) We have volume of air compressed is same in both input and output.
That is A₁x₁ = A₂x₂
A is area and x is the distance moved
x₂ = 0.3 m
Substituting

The input piston moved by 7.5 m