Can you explain how to solve this math problem: Darren decides to do body exercises for a whole week. He does 100 pushups, 50 squats, and 20 dumbbell presses on the first day. On the second day, he does 20 more pushups than on the first day, ten fewer squats, and doubles the number of dumbbell presses. What's the total count of the activities he's done in the two days?