Before Cameron broke his hand he could type 5 × 10 = <<5*10=50>>50 words in 5 minutes.
After he broke his hand he could only type 5 × 8 = <<5*8=40>>40 words in 5 minutes.
The difference between the number of words he could type in 5 minutes before and after he broke his arm is 50 - 40 = <<50-40=10>>10 words.
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