Answer
$(8+r+2t)(8-r-2t)$
Work Step by Step
$\bf{\text{Solution Outline:}}$
To factor the given expression, $
64-(r+2t)^2
,$ use the factoring of the difference of $2$ squares.
$\bf{\text{Solution Details:}}$
Using $a^2-b^2=(a+b)(a-b)$ or the factoring of the difference of $2$ squares, the factored form of the expression above is
\begin{array}{l}\require{cancel}
[8+(r+2t)][(8-(r+2t)]
\\\\=
[8+r+2t][(8-r-2t]
\\\\=
(8+r+2t)(8-r-2t)
.\end{array}