Answer
$6s^4-3t$
Degree $=4$
Type $=$ Binomial.
Work Step by Step
The given expression is
$=(4s^4+2st+t)+(2s^4-2st-4t)$
Clear the parentheses.
$=4s^4+2st+t+2s^4-2st-4t$
Group like terms.
$=4s^4+2s^4+2st-2st-4t+t$
Simplify.
$=6s^4-3t$
The greatest exponent of $s$ is $4$, so the degree of the polynomial is $4$.
There are two terms, so the type of the polynomial is binomial.