It really is impossible to answer this question with so little information. Where are you staying; are you planning to travel round the country and/or take a Nile cruise; do you like expensive meals; etc, etc? Better than asking on this site, would be to consult a good, up-to-date guide book - eg Lonely Planet - which will provide details of costs.
Well, it still depends on what's included in your package - assuming it is a package holiday - in terms of meals, sight-seeing etc; but I would say the equivalent of �20 per day per person should cover it comfortably. See the following website for more info http://www.lonelyplanet.com/destinations/africa/egypt/money. htm (There are about 10 Egyption pounds to one GB pound.)