Answer:
is the expression with value of 15 when n = 7.
Step-by-step explanation:
To find the expression whose value is 15, substitute the value of n = 7 in each given expression.
Expression 1:
![43-5n](https://tex.z-dn.net/?f=43-5n)
Substituting the value of n,
![43-5\left(7\right)](https://tex.z-dn.net/?f=43-5%5Cleft%287%5Cright%29)
Simplifying,
![43-35=8](https://tex.z-dn.net/?f=43-35%3D8)
Since the value of the expression is 8 which is not equal 15.
Hence expression
does not have value of 15 when n = 7.
Expression 2:
![3n-5](https://tex.z-dn.net/?f=3n-5)
Substituting the value of n,
![3\left(7\right)-5](https://tex.z-dn.net/?f=3%5Cleft%287%5Cright%29-5)
Simplifying,
![21-5=16](https://tex.z-dn.net/?f=21-5%3D16)
Since the value of the expression is 16 which is not equal 15.
Hence expression
does not have value of 15 when n = 7.
Expression 3:
![6n-28](https://tex.z-dn.net/?f=6n-28)
Substituting the value of n,
![6\left(7\right)-28](https://tex.z-dn.net/?f=6%5Cleft%287%5Cright%29-28)
Simplifying,
![42-28=14](https://tex.z-dn.net/?f=42-28%3D14)
Since the value of the expression is 14 which is not equal 15.
Hence expression
does not have value of 15 when n = 7.
Expression 4:
![19-\dfrac{28}{n}](https://tex.z-dn.net/?f=19-%5Cdfrac%7B28%7D%7Bn%7D)
Substituting the value of n,
![19-\dfrac{28}{7}](https://tex.z-dn.net/?f=19-%5Cdfrac%7B28%7D%7B7%7D)
Simplifying,
![19-4=15](https://tex.z-dn.net/?f=19-4%3D15)
Since the value of the expression is 15 which is equal 15.
Hence expression
has the value of 15 when n = 7.