Just FYI typo in 32.7
should be 0755 = u+rwx,g+rx,o+rx
I don't see any typo in 32.7. The section says the following: "For instance, to give the owner and world execute permission, and remove the group write permission:"
Initial situation: 664
Final situation: 745
And you get that running "chmod uo+x,g-w a_file".