Let $\mathfrak{X}$ be a class finite groups closed under taking subgroups, homomorphic images, and extensions, and
let $\mathrm{k}_{\mathfrak{X}}(G)$ be the number of conjugacy classes $\mathfrak{X}$-maximal subgroups of a finite group $G$.
The natural problem calling for a description, up to conjugacy, of
the $\mathfrak{X}$-maximal subgroups of a given finite group is not inductive.
In particular, generally speaking, the image of an $\mathfrak{X}$-maximal
subgroup is not $\mathfrak{X}$-maximal in the image of a homomorphism.
Nevertheless, there exist group homomorphisms that preserve the number of conjugacy classes of maximal
$\mathfrak{X}$-subgroups (for example, the homomorphisms whose kernels are $\mathfrak{X}$-groups).
Under such homomorphisms, the image of an $\mathfrak{X}$-maximal subgroup is always $\mathfrak{X}$-maximal,
and, moreover, there is a natural bijection between the conjugacy classes
of $\mathfrak{X}$-maximal subgroups of the image and preimage.
In the present paper, all such homomorphisms are
completely described.
More precisely, it is shown that, for a homomorphism $\phi$
from a group $G$,
the equality $\mathrm{k}_{\mathfrak{X}}(G)=\mathrm{k}_{\mathfrak{X}}(\operatorname{im} \phi)$
holds if and only if $\mathrm{k}_{\mathfrak{X}}(\ker \phi)=1$,
which in turn is equivalent to the fact that the composition factors of the kernel of
$\phi$ lie in an explicitly given list.