How is time child is in possesion calculated?

Asked in Stafford, TX - 7 months

I realize that the NCP pays child support to help CP afford to care for child... supposedly the in my case, the mother of the child has the child 51% of the time. how is this 51% calculated in texas? I have the child in my custody every 1st 3rd and 5th weekend from friday at 3pm until sunday at 6pm and every thursday from 3 to 8pm, plus 30 days in summer and alternating holidays... does summer count? i was told that summer doesn't count because the child is not in school. is this true?