Answer:
20 visits
Step-by-step explanation:
20 is the least common multiple of 4 and 10.
Multiples of 4:
4, 8, 12, 16, 20, 24, 28...
Multiples of 10:
10, 20, 30, 40, 50, 60, 70
After 20 visits, you will receive the discount and a free hair product at the same time.
Hope this helps.
