Answer
$U=-1.49*10^{-26}J$
Work Step by Step
We are given the vectors $\vec{P}$ and $\vec{E}$, so we can use the equation $U=-\vec{P}\cdot\vec{E}$
$\vec{P}=(3.00\hat{i}+4.00\hat{j})(1.24*10^{-30}C*m)$ and $\vec{E}=4000 \frac{N}{C}$
So, taking the dot product, we get the answer:
$U=-\vec{P}\cdot\vec{E}=-(3.00*4000\frac{N}{C}+4.00*0\frac{N}{C})(1.24*10^{-30}C*m)$
$U=-3.00*4000*1.24*10^{-30}J=-1.49*10^{-26}J$
$U=-1.49*10^{-26}J$
