need help with a maths problem!?

here is the question... ewaste is becoming a significant problem with the growing numbers of electronic devices used and quickly discared in society today. Lincoln, ogunseitan and others have reported that 700 million obsikete ohones discarded in 2005 contained an estimated 560 000kg of lead in the form of solder. Australians purchased 40 million mobile phones in the 5 years from 2008-2012. Use the lincoln data to estimate the amount of lead potentially in these mobile phones purchased in australia when they became waste. comment on possible problems with this estimate. using the context explain what the following mean in real world terms: a) 700 million divide 560000 b) 700 million divide 40 million c) 40 million divide 1250