Kraft wants to acquire Cadbury and have placed a value of £10.3bn on Cadbury in September 2009. Assuming that if this acquisition should go ahead Kraft could sell an unwanted production plant in Birmingham for £500m. In addition annual savings was estimated by Kraft to have amount to £390.50m as a results of downsizing and consolidation. However immediate redeployment and location of redundant workforce would have costs £1.5bn. The company's weighted average cost of capital (WACC) is assumed to be 15%. Kraft management stated that the motive of acquiring Cadbury is to obtain synergy. On what basis should synergy be determined? 

Calculate the value of synergy and separately provide impartial impartial advice to both companies.