Answer:
100th customer is the first desired customer who received both the gift cards.
Step-by-step explanation:
$5 gift card is received by every 20th Customer.
⇒ The customers who receive this $5 card are:
20th Customer, 40th Customer , 60th Customer , 80th Customer, <u>100th</u><u> Customer</u>, 120th Customer .... and so on
Also, $10 gift card is received by every 50th Customer.
⇒ The customers who receive this $10 gift are:
50th Customer, <u>100th</u><u> Customer</u> , 150th Customer , 200th Customer ......
Among all the customers the 100th customer is the first customer who receives $5 gift card as well as the $10 gift card.
Hence, 100th customer is the first desired customer who received both the gift cards.
