Answer:
A
Step-by-step explanation:
To rite the equation of the function, take two points from the table. Let them be (1,21) and (3,15).
The slope of the function is
[tex]\dfrac{21-15}{1-3}=\dfrac{6}{-2}=-3[/tex]
Thus, the equation of the function in slope-intercept form is
[tex]f(n)=-3n+b[/tex]
Find b by substituting coordinates of the first point into the function expression:
[tex]21=-3\cdot 1+b\\ \\b=21+3\\ \\b=24[/tex]
Therefore,
[tex]f(n)=-3n+24[/tex]