A survey of 1000 people found that 70% of the people have a CD player, 85% have a telephone and 45.2% have a computer. At least how many people have all three objects?

Well as you can see, this question has me puzzled ( I am a weak computer science student, mathematically). Normally these questions give a bit more to go on like 40 have a pc and cd player etc.

Any help, or guide in the right direction would be great,

thanks everyone,

m.