/usr/share/maxima/5.35.1/demo/ is in maxima-sage 5.35.1-2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/maxima/5.35.1/demo/cf.dem
/usr/share/maxima/5.35.1/demo/demo.dem
/usr/share/maxima/5.35.1/demo/eaton1.dem
/usr/share/maxima/5.35.1/demo/eaton2.dem
/usr/share/maxima/5.35.1/demo/ezgcd.dem
/usr/share/maxima/5.35.1/demo/hypgeo.dem
/usr/share/maxima/5.35.1/demo/macex.dem
/usr/share/maxima/5.35.1/demo/macro.dem
/usr/share/maxima/5.35.1/demo/manual.demo
/usr/share/maxima/5.35.1/demo/newfac.dem
/usr/share/maxima/5.35.1/demo/plots.mac
/usr/share/maxima/5.35.1/demo/romberg.dem
/usr/share/maxima/5.35.1/demo/sumcon.dem
/usr/share/maxima/5.35.1/demo/trgsmp.dem