7. Car A and Car B start from locations $\mathrm{A}$ and $\mathrm{B}$ respectively at the same time, heading towards each other, and meet at point $\mathrm{C}$, which is 1600 meters from $\mathrm{A}$. After meeting, Car B maintains its speed, while Car A's speed is halved. Car A continues to drive to $\mathrm{B}$ and immediately turns around. When Car A reaches $\mathrm{C}$ again, Car B has just arrived at $\mathrm{A}$ for the first time.
The distance between $\mathrm{A}$ and $\mathrm{B}$ is $\qquad$ meters.
$2400$