Which of the following situations would combine to make zero?
a.
julia took two math practice tests last month. she plans to take two more tests later this month.
b.
chris walks four blocks west to the grocery store. after buying groceries, he walks four blocks east.
c.
manuel spent five hours exercising this weekend. he also spent five hours watching television.
d.
amy drives for three hours along an interstate highway. she then drives for three hours along county highways.