Jed collects stamp cards. Every week, he gets 6 cards. But every two weeks, he gives 2 cards to his friends. If Jed started with 20 cards, after how many weeks will he have a total of 40 cards?
Thoughts? Step-by-step reasoning:
In the first week, Jed has 20 + 6 = 26 cards. In the second week, he has 26 + 6 = 32 cards. But he is left with 32 - 2 = 30 cards on the 2nd week after giving 2 cards to his friend. Then Jed has 30 + 6 = 36 cards on the 3rd week. He has 36 + 6 = 42 cards on the 4th week. After giving his friend 2 cards, he is then left with 42 - 2 = 40 cards on the 4th week. Hence, Jed will have a total of 40 cards in 4 weeks.
Thus, the answer is 4.