Final answer:
Zack spent 51 minutes on parking each day.
Step-by-step explanation:
To find the amount Zack spent on parking each day, we need to first determine the total amount he spent each day. On Monday, he spent a total of 68 minutes parking and 34 minutes shopping, which is 102 minutes in total. On Thursday, he spent a total of 143 minutes parking and 31 minutes shopping, which is 174 minutes in total.
Since Zack spent the same total amount on parking and shopping each day, we can divide the total time by 2 to get the amount he spent on parking each day. Therefore, Zack spent 51 minutes on parking each day.