The ideal mechanical advantage (IMA) of a device is the mechanical advantage with the assumption there are no frictions acting in the machine. In this case, the IMA is equal to
[tex]IMA= \frac{F_{out}}{F_{in}}[/tex]
where [tex]F_{out} [/tex] is the load (the output force of the machine) while [tex]F_{in} [/tex] is the force applied in input.
In our problem the output force is 245 N and the input force is 245 N, so the ideal mechanical advantage is
[tex]IMA= \frac{245 N}{245 N}=1 [/tex]
