جَاءَتِ اثْنَتَا عَشْرَةَ طَالِبَةً — Twelve female students came.
اثْنَتَا: nominative subject marked by alif on the dual pattern.
عَشْرَةَ: second part fixed on fatḥ.
طَالِبَةً: accusative numerical specification.
رَأَيْتُ اثْنَتَيْ عَشْرَةَ طَالِبَةً — here «اثْنَتَيْ» is accusative with yāʾ. This is an added feminine parallel to the book’s masculine twelve example.