Answer:
The average number of customers per day during the sale was 150.
Explanation:
This question can be solved using a rule of three.
Before the sale, the average number of customers per day was 120, which is 100% = 1.
Now, there are x customers, and since it is an increase of 25%, it is 100+25 = 125% = 1.25. So
120 - 1
x - 1.25
x = 1.25*120 = 150
The average number of customers per day during the sale was 150.