Answer
$t^2-t-12$
Work Step by Step
Using $(a+b)(c+d)=ac+ad+bc+bd$ or the product of $2$ binomials, the given expression, $
(t-4)(t+3)
$, is equivalent to
\begin{array}{l}\require{cancel}
t(t)+t(3)-4(t)-4(3)
\\\\=
t^2+3t-4t-12
\\\\=
t^2-t-12
.\end{array}