###Human: Brian goes fishing twice as often as Chris, but catches 2/5 times fewer fish than Chris per trip. If Brian caught 400 fish every time he went fishing, how many fish did they catch altogether if Chris went fishing 10 times?, ### Assistant: If Brian caught 400 fish in one trip, he caught 2*400=800 fish in two trips.
Since Brian catches 2/5 times less fish than Chris per trip, Chris catches 2/5*400=160 more fish in one fishing trip.
Chris's total number of fish in one trip is 400+160 = 560 fish.
In 10 trips, Chris catches 560*10=5600 fish.
If in his two trips Brian catches 800 fish, and he goes fishing twice as often as Chris, if Chris goes fishing 10 times, Brian will catch 800*10=8000 fish.
The total number of fish they'll catch if Chris goes fishing ten times is 8000+5600=13600 
 So the answer is :  13600