Answer
$\lt -3, -4 \gt$
Work Step by Step
As we know that the unit vector $\hat{\textbf{u}}$ is defined as: $\hat{\textbf{u}}=\dfrac{v}{|v|}$
Now, we have, $|v|=\sqrt{(\dfrac{3}{5})^2+(\dfrac{4}{5})^2}=1$
Thus, $\hat{\textbf{u}}=\dfrac{v}{|v|}=\dfrac{\lt \dfrac{3}{5},\dfrac{4}{5} \gt}{1}= \lt \dfrac{3}{5},\dfrac{4}{5} \gt$
and $-5 \hat{\textbf{u}}=-5\lt \dfrac{3}{5},\dfrac{4}{5} \gt =\lt -3, -4 \gt$
