You can put this solution on YOUR website! Recall that which means that the distance is equal to the rate multiplied by time. Since he "runs 350 meters in 17 seconds", we can say that and .
Plug these values in to get . Now solve for 'r' to get . So his average speed is about 20.588 meters per second. Note: this converts to about 46.05 mph, so either the book isn't being realistic or there's a typo somewhere.