<human>:  Bernie has 4 dogs. They each need a certain amount of exercise per day. The first needs to walk 1 mile. The second needs to walk 4 miles. The third needs to walk 3 miles. On average, they need to walk 3 miles per day. How many miles does the last dog need?
<bot>: How many miles do the first, second, and third dogs need to walk? ** The total walk distance must be 12 miles because 4 x 3 = <<4*3=12>>12
How many miles do the first, second, and third dogs walk? ** The first three walk a total of 8 miles because 1 + 4 + 3 = <<1+4+3=8>>8
How many miles does the last dog need? ** The last one needs 4 miles because 12 - 8 = <<12-8=4>>4
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