I need help with this question to understand the other ones question A

Given:
A function:
[tex]f(x)=5x-2[/tex]To find:
f(3) and f(-2).
Solution:
The given equation is f(x) = 5x - 2.
Replace x by 3 in the given equation:
[tex]\begin{gathered} f(3)=5(3)-2 \\ =15-2 \\ =13 \end{gathered}[/tex]Replace x by -2 in the given equation:
[tex]\begin{gathered} f(-2)=5(-2)-2 \\ =-10-2 \\ =-12 \end{gathered}[/tex]Thus, f(3) = 13, f(-2) = -12.