Answer:
[tex]19-\frac{28}{n}[/tex] is the expression with the 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:
[tex]43-5n[/tex]
Substitute the value of n & simplify,
[tex]43-5(7)[/tex]
[tex]43-35=8[/tex]
Since the value of the expression is 8 which is not equal 15.
Hence expression [tex]43-5n[/tex] does not have value of 15 when n = 7.
Expression 2:
[tex]3n-5[/tex]
Substituting the value of n & simplify,
[tex]3(7)-5[/tex]
[tex]21-5=16[/tex]
Since the value of the expression is 16 which is not equal 15.
Hence expression [tex]3n-5[/tex] does not have value of 15 when n = 7.
Expression 3:
[tex]6n-28[/tex]
Substituting the value of n & simplify,
[tex]6(7)-28[/tex]
[tex]42-28=14[/tex]
Since the value of the expression is 14 which is not equal 15.
Hence expression [tex]6n-28[/tex] does not have value of 15 when n = 7.
Expression 4:
[tex]19-\frac{28}{n}[/tex]
Substituting the value of n & simplify,
[tex]19-\frac{28}{7}[/tex]
[tex]19-4=15[/tex]
Since the value of the expression is 15 which is equal 15.
Hence expression [tex]19-\frac{28}{n}[/tex] has the value of 15 when n = 7.
