This is a charade with reversals - multiple parts are combined, with some elements reversed or turned around as indicated by directional words.
Look for 'back' and 'travelling west' as reversal indicators. You need: a word for 'way' reversed, plus 'about' + Roman numeral 5 + half of 'days', all reversed together.
Answer: ADVERTS | ST (street/way) reversed gives TS, then RE (about) + V (Roman 5) + DA (half of 'days') reversed gives ADVER, combining to make ADVERTS backwards becomes STREVDA... wait, that's wrong. Actually: RE + V + DA reversed gives ADVER, then TS after it makes ADVERTS.