P, Q, R, S, T, U and V are seven professors. Each one teaches a different subject from Physics, Chemistry, Biology, English, Mathematics, Economics and Geography not necessarily in the same order. Each of them teaches one day each on sevens days of the week from Monday to Sunday not necessarily in the same order. R teaches Biology on Friday. Q teaches Mathematics on the previous day of the day on which the professors teaches Physics. V teaches on Sunday but does not teach Chemistry, or English. S teaches Economics on the previous day on which U teaches. P teaches Geography Tuesday T dues not teach English.
Which subject does U teach?
