Given:
[tex]\begin{gathered} f(1)=3 \\ f(n)=f(n-1)+4 \end{gathered}[/tex]We need to find f(5)
so,
[tex]\begin{gathered} f(1)=3 \\ f(2)=f(1)+4=3+4=7 \\ f(3)=f(2)+4=7+4=11 \\ f(4)=f(3)+4=11+4=15 \\ \\ f(5)=f(4)+4=15+4=19 \end{gathered}[/tex]So, the value of f(5) = 19