Alice and Bob each have a certain amount of money. If Alice receives n dollars from Bob, then she will have 3 times as much money as Bob. If, on the other hand, she gives n dollars to Bob, then she will have 2 times as much money as Bob. If neither gives the other any money, what is the ratio of the amount of money Alice has to the amount Bob has?

1 answer

Let \( A \) be the amount of money Alice has, and \( B \) be the amount of money Bob has. We have two scenarios based on the transfers of \( n \) dollars:

  1. Alice receives \( n \) dollars from Bob:

    • After this transaction, Alice's new amount will be \( A + n \) and Bob's will be \( B - n \).
    • According to the problem, we have: \[ A + n = 3(B - n) \]
  2. Alice gives \( n \) dollars to Bob:

    • After this transaction, Alice's new amount will be \( A - n \) and Bob's will be \( B + n \).
    • According to the problem, we have: \[ A - n = 2(B + n) \]

Now we will simplify both equations.

Simplifying the equations

From the first equation: \[ A + n = 3(B - n) \] Expanding this gives: \[ A + n = 3B - 3n \] Rearranging terms results in: \[ A + n + 3n = 3B \] \[ A + 4n = 3B \quad (1) \]

From the second equation: \[ A - n = 2(B + n) \] Expanding this gives: \[ A - n = 2B + 2n \] Rearranging terms results in: \[ A - n - 2n = 2B \] \[ A - 3n = 2B \quad (2) \]

Solve the system of equations

Now we have the system:

  1. \( A + 4n = 3B \)
  2. \( A - 3n = 2B \)

We will express \( A \) in terms of \( B \) and \( n \) from both equations:

From equation (1): \[ A = 3B - 4n \]

From equation (2): \[ A = 2B + 3n \]

Setting these two expressions for \( A \) equal to each other: \[ 3B - 4n = 2B + 3n \]

Now, solving for \( B \): \[ 3B - 2B = 4n + 3n \] \[ B = 7n \]

Next, substituting \( B \) back into one of the expressions for \( A \): Using \( A = 2B + 3n \): \[ A = 2(7n) + 3n = 14n + 3n = 17n \]

Find the ratio \( \frac{A}{B} \):

Now we have \( A = 17n \) and \( B = 7n \): \[ \frac{A}{B} = \frac{17n}{7n} = \frac{17}{7} \]

Thus, the ratio of the amount of money Alice has to the amount Bob has is: \[ \boxed{\frac{17}{7}} \]