We know that function h outputs the value of b when we input a value of a, that means:
[tex]b=h(a)[/tex]To find the expression for h we just need to solve the equation given for b, let's do that:
[tex]\begin{gathered} 3a-5=-4b+1 \\ -4b=3a-5-1 \\ -4b=3a-6 \\ b=\frac{3a-6}{-4} \\ b=-\frac{3}{4}a+\frac{6}{4} \\ b=-\frac{3}{4}a+\frac{3}{2} \end{gathered}[/tex]Therefore, we have that:
[tex]h(a)=-\frac{3}{4}a+\frac{3}{2}[/tex]