3200≥1200+600+675 Because, the phone plan only allows at maximum 3200 minutes, meaning that all of the minutes the family has used has to be less than or equal to 3200 minutes (Or 3200 minutes is greater than the amount of minutes used by the Cruz family)
1/2 of 20 is 20/2 which is 10.
All you really need to do here is to divide 20 by 2 to get 10.