7. In the polar coordinate system, the distance from point $M \left( 4 , \frac { \pi } { 3 } \right)$ to the line $l : \rho ( 2 \cos \theta + \sin \theta ) = 4$ is $d =$ $\_\_\_\_$.
7. In the polar coordinate system, the distance from point $M \left( 4 , \frac { \pi } { 3 } \right)$ to the line $l : \rho ( 2 \cos \theta + \sin \theta ) = 4$ is $d =$ $\_\_\_\_$.