The total number of customers last week was 5417 → this number represents the 100% of customers you've had.
For the next week you expect a 2.4% increase, this means that you expect to welcome the number of customers (100%) of last week plus 2.4% more
You can use cross multiplication to determine how many customers you expect for the next week:
100% ____ 5417
102.4% ___ x
Both relationships are at the same ratio so that:
You expect to receive 5547 customers this week