Here let force on piston 1 be F1
cross sectional area of piston 1, A1=2 cm2
force on piston 2 be F2=150 N
cross sectional area of piston 2, A2=12 cm2
we know that the pressure on smaller piston(1) is equal to the pressure on wider piston(2) in a hydraulic machine.
P1=P2
So, F1A1=F2A2
⇒F12 cm2=150 N12 cm2
⇒F1=25N
Hence, the force on smaller piston is 25 N.