Answer:
40th costumer
Step-by-step explanation:
The 40th costumer will receive a free cookie and drink. You need to find factors of 4 and factors of 10. Then when you find 4 and 10 have the same factor that’s your answer. So you do 4,8,16,24,32,36,40,44,48, etc. (counting up by 4) now do it to 10,20,30,40,50,60,70, etc. (counting up by 10) Now you notice that the first number that is the same is 40. So that means the 40th costumer will be the first one to receive a free drink and cookie.
