The athlete's average speed was 300 meters/minute.
<h3>How to calculate the speed of the athlete?</h3>
To calculate the speed of the athlete we must perform the following operations.
Divide the distance into the total time:
Transform the value from seconds to minutes, for which we must multiply 5 by 60 because each minute is made up of 60 seconds.
- 5m/sec × 60sec = 300m/min
According to the above, the average speed of the athlete is 300m/min.
Learn more about speed in: brainly.com/question/7359669
Based on the calculations, the unknown number is equal to 
- Let the unknown number be x.
<h3>How to find an
unknown number:</h3>
Translate the word problem into an algebraic expression, we have;
Adding 21 to the unknown number:
Multiplying the result by 3:
84 more than two-thirds of the unknown number:
Equating the equations, we have:
Cross-multiplying, we have:
Read more on word problems here: brainly.com/question/13170908
Answer:
The Acceleration, In Centimeters Per Second Per Second, Of A Projectile Is Modeled By A (T) = 21" - 156 + 36, Where T Is Measured in seconds
