To find out how many calls each volunteer has to make to reach the goal of 280 calls, we first need to determine the total number of volunteers.
The group has 4 groups of 7 volunteers, which means:
4 groups × 7 volunteers/group = 28 volunteers.
Next, we divide the total number of calls by the total number of volunteers to find out how many calls each volunteer needs to make:
280 calls ÷ 28 volunteers = 10 calls per volunteer.
Therefore, each volunteer has to make 10 calls to reach the goal of 280 calls.