Answer
$3w^2-6wz+\dfrac{1}{4}wz-\dfrac{1}{2}z^2$
Work Step by Step
Using $(a+b)(c+d)=ac+ad+bc+bd$ or the FOIL Method, the product of the binomials in the given expression, $
\left( 3w+\dfrac{1}{4}z \right)( w-2z )
,$ is
\begin{array}{l}\require{cancel}
3w(w)+3w(-2z )+\dfrac{1}{4}z(w)+\dfrac{1}{4}z(-2z)
\\\\=
3w^2-6wz+\dfrac{1}{4}wz-\dfrac{1}{2}z^2
.\end{array}