First = <<14=14>>14 oz
Second = (1/2) * 14 = <<(1/2)*14=7>>7 oz
Third = 7 + 5 = <<7+5=12>>12 oz
14 + 7 + 12 = <<14+7+12=33>>33 oz
There are 33 ounces of cereal in those 3 boxes.
#### 33