Given:
The length of field is n yards.
The length of a field in feet is a function f(n).
To find:
The function rule for this situation.
Solution:
We know that,
1 yard = 3 feet
Using this conversion, we get
n yard = 3n feet
The length of field is n yards. So, the length of the field is 3n feets.
The length of a field in feet is a function f(n). So,

Therefore, the required function rule for this situation is
.