I just want to know if this equation for the mass defect is correct.

 

$$\Delta m = Z * m_p + Z * m_e + N* m_n - A $$

 

$A = $ mass number

No.
A is the mass of an $^A_Z X$ atom.

I came up with another formula also $$ΔM=[(Z(m_p)+N(m_n))−(M)]$$ where m is the observed mass.

This is correct if $(M)$ is the mass of an $^A_Z X$ nucleus.

I just want to know if this equation for the mass defect is correct.

$$\Delta m = Z * m_p + Z * m_e + N* m_n - A $$

$A = $ mass number

No.
A is the mass of an $^A_Z X$ atom.

I came up with another formula also $$ΔM=[(Z(m_p)+N(m_n))−(M)]$$ where m is the observed mass.

This is correct if $(M)$ is the mass of an $^A_Z X$ nucleus.