You can never have repeating x-values. You can have repeating y-values though. Whenever determining whether something is a function, just look at whether it has repeating x-values or not. If it does, it is not a function. If it doesn't, it is a function.
First you divide 1200 by 25 (1200/25) it comes out to 48. That means the he types at a rate of 48wpm. So then all you have to do is multiply 48 and 45 and you get 2160 words.
