August solved a math problem that had an answer twice as big as the answer of the first math problem, meaning the next answer was 600*2 = <<600*2=1200>>1200
The first math problem and the second math problem has answers totaling 1200+600 = <<1200+600=1800>>1800
The third math problem had an answer 400 less than the combined total answers of the first and the second math problems, meaning the third answer was 1800-400 = <<1800-400=1400>>1400
Altogether, the math problems that August solved on his computer had answers totaling 1800+1400= <<1800+1400=3200>>3200
#### 3200