Final answer:
To find the length of each boxcar, we can use the equation length of each boxcar multiplied by the number of boxcars equals the total length. Applying this equation to the given problem, we find that each boxcar is 7 inches long.
Step-by-step explanation:
To solve this problem, we can use the equation
In this case, the length of each boxcar is the unknown we are trying to find, the number of boxcars is 3, and the total length is 21 inches.
So, the equation will be where x represents the length of each boxcar. To find x, we need to divide both sides of the equation by 3. Thus, x=7
Therefore, each boxcar is 7 inches long.