City sources predict the FTSE 100 will open up 89 points from Friday's close of 5,435, boosted by the news that debt-laiden economy Spain has secured itself a 100bn euro rescue deal for its troubled banks. The package was authorised by the EU over the weekend. Supermarket giant Tesco was putting a brave face on things as like-for-like (LFL) sales continued to decline in UK stores in the group's first quarter, as expected. In the 13 weeks ending May 26th, UK sales including value added tax (VAT) and petrol grew by 2.1% and by 2.0% excluding petrol. LFL sales, excluding both VAT and petrol, reduced by 1.5% in the quarter. Tesco said the UK performance was in line with expectations.Commodities producer and marketer Glencore has completed the purchase of a majority interest in Namibian zinc mining group Rosh Pinah Zinc Corporation. Rosh Pinah operates an underground zinc/lead mine in south-western Namibia, 800km south of the capital Windhoek. In 2011, the mine produced 89,000 tonnes of zinc concentrate and 16,000 tons of lead concentrate in 2011. No financial information relating to the acquisition was disclosed.Serco Group, the international services company, has increased its public sector exposure with the purchase of Vertex Public Sector for 55.5m pounds. The company said the move would support expansion into new areas of middle and back office support and add further scale to its recently created Global Services division.