Explanation:
To find Johnny's reading rate in words per minute (WPM), you can simply divide the number of words he read by the time it took him to read them.
Johnny read 300 words in 6 minutes, so:
Reading Rate (WPM) = Number of Words / Time (in minutes)
Reading Rate (WPM) = 300 words / 6 minutes
Reading Rate (WPM) = 50 words per minute
Johnny is reading at a rate of 50 words per minute.