does anyone know what bus to take to lax airport from union rescue mission on skid row in los angeles ca? thank you

As a foreigner I'd consult my LA Lonely Planet Guide for info and I find the Best direct bus is from Pershing Square which is close to the Skid row District (You'll have to ask again if there is an Information office open?) I did find this selection of postings which may be of help choosing which service is most Frequent.
Try this link too this will get you to Pershing Square (and with the right Bus only 1 stop?)

Not much help but its a starting point