The Solution:
The correct answer is [option 3]
Given the function:
[tex]f(x)=2(x+3)[/tex]
We are required to find the value of f(15).
We shall substitute 15 for x in the given function.
[tex]f(15)=2(15+3)=2\times18=36_{}[/tex]
Thus, we start by substituting 15 for x and then simplify to get f(15) =36.
Therefore, the correct answer is [option 3]
