Within the next 90 days, the City of Detroit will demolish 1,500 abandoned and dangerous houses, Detroit Mayor Dave Bing pledged Tuesday. To date, the Bing administration has demolished 4,500 houses, and the 90-day blitz will bring the total to 6,000, Bing said. The mayor promised to demolish at least 10,000 during his four-year term. Bing said when he first came into office, it cost the city about $10,000 to demolish one house, but the city has negotiated the price down with contractors to about $8,500. Karla Henderson, Bing’s group executive for planning and facilities, said the 1,500 housing demolitions will cost $13 million to $15 million. The city had run out of demolition money, she said, but officials were able to amend boundaries of where demolition grant money was funded through HUD’s Neighborhood Stabilization Program 2 to include a wider area around various schools.