Answer
$y^{10b+3}$
Work Step by Step
Using the laws of exponents, the given expression, $
\dfrac{\left( y^{4b} \right)^3}{y^{2b-3}}
,$ simplifies to
\begin{array}{l}\require{cancel}
\dfrac{y^{4b(3)}}{y^{2b-3}}
\\\\=
\dfrac{y^{12b}}{y^{2b-3}}
\\\\=
y^{12b-(2b-3)}
\\\\=
y^{12b-2b+3}
\\\\=
y^{10b+3}
.\end{array}
