Three Dimensional Geometry

$\mathbf{r} \cdot(\hat{\mathbf{i}}+4 \hat{\mathbf{j}})=13$

$\mathbf{r} \cdot(\hat{\mathbf{i}}+6 \hat{\mathbf{j}}+\hat{\mathbf{k}})=18$

$\mathbf{r} \cdot(\hat{\mathbf{i}}+2 \hat{\mathbf{j}}-\hat{\mathbf{k}})=8$

$\mathbf{r} \cdot(\hat{\mathbf{i}}+8 \hat{\mathbf{j}}+2 \hat{\mathbf{k}})=23$