$3$: A system contains $4$ discrete particles. The particles have the following mass and position vector:

$3$

$q,$

$m_1=5kg$ and $\frac{?}{\text{b}\text{a}\text{r}}(r{)}_1=2$hat$(i)+3$hat$(j)$ meters

$m_2=7kg$ and $\frac{?}{\text{b}\text{a}\text{r}}(r_2)=-2$hat$(i)-3$hat$(j)$ meters

$m_3=2kg$ and $\frac{?}{\text{b}\text{a}\text{r}}(r_3)=$hat$(i)+4$hat$(j)$ meters

$m_4=11kg$ and $\frac{?}{\text{b}\text{a}\text{r}}(r{)}_4=7$hat$(i)-3$hat$(j)$ meters

$3$a: What is the total mass of the system in kg $?$