The Philadelphia region set a record this month, though it’s a bit of a dubious distinction: Thirty-one percent of houses sold here involved a cut in price. A survey of major metropolitan areas by the real estate search engine Trulia, which has been tracking this information for 10 months, showed price reductions hit historic levels in 15 of the 50 cities studied. Philadelphia ranked 11th among the 15 record-setting cities, with the average price reduction thus far in November amounting to 9% and the total amount of reductions equaling $73.3 million.