#### Answer

$-3t^2+4t$

#### Work Step by Step

We start with the given expression: $2t^2+4t-5t^2$
To simplify an algebraic expression, we must eliminate any parentheses and combine like terms.
We use the commutative property to rearrange the expression such that like terms are next to each other: $2t^2-5t^2+4t$
We combine like terms using subtraction: $-3t^2+4t$