Chen Dabai and Gun Core came first.

When A reaches the midpoint, B turns left (1760/2)/11* 9 = 720.

The surplus is 1760/2=880.

B keep it at 1760-720= 1040.

When the speed ratio of Party A and Party B becomes 9: 1 1, let Party A's speed be 9m/s and Party B's speed be1/m/s,

Then: A left 880/9 = 97.78.

B walked the whole journey of1040/11= 94.5445.

The time unit difference is 97.77778-94.5454=3.23233.

So b arrived first;