The latest CD from the pop group "The Irrationals" has twelve songs on it. Each song costs $$99$$p to download from the internet. Alternatively, you could download the whole CD for £$$8.99$$  How much money do you save by purchasing the whole CD rather than buying all twelve tracks separately? 
Overseas Competition->Knowledge Point->Word Problem Modules->Questions Involving Sum, Difference and Multiples->Problems of Difference and Multiple->Difference and Multiples of Multiple Variables