If your machine has a mechanical advantage of 2.5, then WHATEVER force you apply to the input, the force at the output will be 2.5 times as great.
If you apply 1 newton to the machine's input, the output force is
(2.5 x 1 newton) = 2.5 newtons.
If you apply 120 newtons to the machine's input, the output force is
(2.5 x 120 newtons) = 300 newtons.
