Question

Which expression has a value of 15 when n = 7?

1: 43 minus 5 n
2: 3 n minus 5
3: 6 n minus 28
4: 19 minus StartFraction 28 Over n EndFraction

Answer 1

`19-(28)/(n)` is the expression with the value of 15 when n = 7

Explanation:

To find the expression whose value is 15, substitute the value of n = 7 in each given expression.

Expression 1:

`43-5n`

Substitute the value of n & simplify,

`43-5(7)`

`43-35=8`

Since the value of the expression is 8 which is not equal 15.

Hence expression
`43-5n` does not have value of 15 when n = 7.

Expression 2:

`3n-5`

Substituting the value of n & simplify,

`3(7)-5`

`21-5=16`

Since the value of the expression is 16 which is not equal 15.

Hence expression
`3n-5` does not have value of 15 when n = 7.

Expression 3:

`6n-28`

Substituting the value of n & simplify,

`6(7)-28`

`42-28=14`

Since the value of the expression is 14 which is not equal 15.

Hence expression
`6n-28` does not have value of 15 when n = 7.

Expression 4:

`19-(28)/(n)`

Substituting the value of n & simplify,

`19-(28)/(7)`

`19-4=15`

Since the value of the expression is 15 which is equal 15.

Hence expression
`19-(28)/(n)` has the value of 15 when n = 7.