Sam typed 570 words and 15 minutes if he continues to type at this rate how many words will he have typed in two hours

So first, you will have to find out how many words he types in 1 minute, so you divide 570 by 15 and then you'll get 38, so Sam types 38 words per minute. 
Then, we know that 2 hours is equal to 120 minutes. So you multiply 38 by 120 because you want to calculate how many words Sam types in 120 minutes. 
So your answer should be 4,560 words in 2 hours. 

I hope this helped (:

120 minutes in 2 hours
120/15=8
570*8=4560 words
Hope this helps!