For me, Opus got it in two tries: >jack has 15 sisters, each sister has 3 brothers. How many brothers does jack have? Let's approach this step-by-step: 1) We

For me, Opus got it in two tries: >jack has 15 sisters, each sister has 3 brothers. How many brothers does jack have? Let's approach this step-by-step: 1) We know that Jack has 15 sisters. 2) Each of Jack's sisters has 3 brothers. 3) Since all the sisters are Jack's siblings, they share the same brothers. In other words, the brothers of one sister are the same as the brothers of any other sister. 4) Therefore, the number of brothers that Jack has is the same as the number of brothers each of his sisters has. 5) We are told that each sister has 3 brothers. Therefore, Jack has 3 brothers. > Nope You're right, I made an error in my reasoning. Let me try again: 1) Jack has 15 sisters. 2) Each of Jack's sisters has 3 brothers. 3) Jack is one of the brothers of each of his sisters. 4) Therefore, the total number of brothers (including Jack) is 3. 5) To find the number of brothers Jack has, we need to subtract Jack from the total number of brothers. 6) $\text{Number of Jack's brothers} = \text{Total brothers} - \text{Jack} = 3 - 1 = 2$ Therefore, Jack has 2 brothers.