Here is my transcription. I've edited a couple of words. The semicolon / z-like mark can be used for et/ed as well, as here. Abbreviations in square brackets.
1) Alcuinis . Quattuor modis op[er]atur deus.
2) Primo in u[er]bo .ii. in mat[er]ia informi .Un[de]. qui viv[it] in e-
3) ternum creavit om[n]ia simul .tercio. p[er] op[er]a .vi. dier[um] va-
It says Vn~, so vn with a general mark of abbreviation. This mark normally stands for -de if it is written above an -n at the end of a word (provided that -de fits), so it must be unde here, "whence".
I've found an 18th-century print edition of the Sententiae of Petrus Lombardus that has a similar use of unde with partly the same text, and ...