How ??
Force:-
We know
According to newtons second law
[tex]\boxed{\sf Force=Mass\times Acceleration}[/tex]
[tex]\\ \sf\longmapsto Force=kgm/s^2[/tex]
We don't use it
[tex]\\ \sf\longmapsto Force=Newton(N)[/tex]
Hence its a derived unit.
Pressure:-
[tex]\\ \sf\longmapsto Pressure=\dfrac{Force}{Area}[/tex]
[tex]\\ \sf\longmapsto Pressure=\dfrac{N}{m^2}[/tex]
[tex]\\ \sf\longmapsto Pressure=Pascal(Pa)[/tex]
Hence its a derived unit