A typical angiosperm embryo sac at maturity is :

The mature angiosperm embryo sac (commonly the Polygonum type) is formed after the megaspore undergoes three rounds of mitotic division without cytokinesis, producing eight nuclei.

These eight nuclei become organized into seven distinct cells:

• One egg cell (contains one nucleus).
• Two synergid cells (each contains one nucleus, total two nuclei).
• Three antipodal cells (each contains one nucleus, total three nuclei).
• One central (or binucleate) cell that retains two polar nuclei, so this single cell holds two nuclei.

Adding the nuclei: 1 (egg) + 2 (synergids) + 3 (antipodals) + 2 (polar nuclei in the central cell) = $8$ nuclei.

The number of cells is the count of distinct cellular compartments: 1 egg + 2 synergids + 3 antipodals + 1 central cell = $7$ cells.

Therefore, a typical mature angiosperm embryo sac is 8-nucleate and 7-celled.