Answer
$-1$
Work Step by Step
Recall:
The sum of two numbers with oppposite signs is equal to the difference between their absolute values. (the sign of the number with the bigger absolute value must be followed).
Since $|3|=3$ and $|-4|=4$, and $4>3$, then
\begin{align*}
3+(-4)&=-\left(|4|-|3|\right)\\
&=-(4-3)\\
&=-(1)\\
&=-1
\end{align*}
