5k race surveyed runners about their finishing times (f) and the number of previous races they had run (n). the organizers found a negative linear relationship between f and n that is best modeled by the equation f=−1.2n+38.1

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 The first thing we must do for this case is to define variables.
 n = number of 5k races covered
 f = end time.
 We have the following equation:
 f = -1.2n + 38.1
 We note that the slope of the line is:
 m = -1.2 minutes per race
 Therefore, the time decreases 1.2 minutes when the number of races increases n.
 
 The model predicts that for each additional race to runner has run, the finishing time decreases by about 1.2 minutes