Long ride

I drove a car from Beijing to Shanghai. From the start, I drove faster then the expected (a planned stable speed) speed by $\frac{1}{9}$ , so I am early by one and a half hour when reaching Shanghai.

When I decided to go back to Beijing, I drove at the expected speed until after 280 km. After 280 km, I rise the speed of the car up by $\frac{1}{6}$ , so I am early by 1 hour and 40 minute when reaching Beijing.

What is the distance from Beijing to Shanghai? (Assume the distance is not accurate.)