Answer
$-3t^3-t^2-t+6$
Work Step by Step
Removing the grouping symbols, then the given expression, $
(7+t-5t^2+2t^3)-(1+2t-4t^2+5t^3)
$, is equivalent to
\begin{array}{l}
7+t-5t^2+2t^3-1-2t+4t^2-5t^3
.\end{array}
By combining like terms, then
\begin{array}{l}
(2t^3-5t^3)+(-5t^2+4t^2)+(t-2t)+(7-1)
\\\\=
-3t^3-t^2-t+6
.\end{array}
