Answer:
1600
Explanation:
We can setup a ratio in terms of words per minute.
Mr. Brown can type 80 words in 2 minutes, so our ratio looks like this:
40:2
In order to find how many words he can type in 40 minutes, we must set the minutes side of our ratio to 40. In order to do that, we must multiply our minutes side by a factor that makes it equal 40, and then multiply the words side by the same factor. We can divide 40 by 2 to figure out the factor, which is 20. Since the factor is 20, we must multiply it by the words side to figure out how many words he types in 40 minutes, which is 20 ยท 80 = 1600 words.