Answer
$20x^2-32x-16$
Work Step by Step
The student added the first terms and the last terms, which is not how multiplying two binomials is done.
Using the FOIL Method, which is given by $(a+b)(c+d)=ac+ad+bc+bd,$ the expression, $(4x-8)(5x+2),$ is
\begin{array}{l}\require{cancel}
(4x-8)(5x+2)
\\\\=
4x(5x)+4x(2)-8(5x)-8(2)
\\\\=
20x^2+8x-40x-16
\\\\=
20x^2-32x-16
.\end{array}
