We have to find the customers who receive a free drink and a free sandwich separately and then find the common between the two sets of customers
Since every 8th customer receives a free drink, these customers would be 8, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88, 96, 104, 112, 120, 128, 136, 144, 152, 160, 168, 176, 184, 192 and 200
Since every 12th customer receives a free sandwich, these customer would be: 12, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, 180 and 192
So the common customers among the two sets are customers 24, 48, 72, 96, 120, 144, 168 and 192
So the number of common customers are 8 in number
Conclusion: 8 customers will received both a free drink and a free sandwich
