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Question

Seven times the present age of P exceeds the present age of Q by 46 years. After 8 years, six times Q's age will be 24 years less than six times P's age at that time. What is the present age (in years) of Q?

The correct answer is
3

Seven Times P Age Relation

This problem asks us to find the current age of Q based on relationships involving the ages of P and Q. We will use algebra to set up and solve equations representing these relationships.

Let $P$ represent the present age of person P, and let $Q$ represent the present age of person Q.

First Condition: Present Ages

The problem states: "Seven times the present age of P exceeds the present age of Q by 46 years." This translates directly into an algebraic equation:

$7P = Q + 46$

We can rewrite this equation as:

$7P - Q = 46 \quad (1)$

Ages After 8 Years Setup

The problem also describes a situation 8 years from now. In 8 years:

  • P's age will be $P + 8$.
  • Q's age will be $Q + 8$.

The second condition is: "six times Q's age will be 24 years less than six times P's age at that time." This gives us the equation:

$6(Q + 8) = 6(P + 8) - 24$

Let's simplify this equation:

$6Q + 48 = 6P + 48 - 24$

$6Q + 48 = 6P + 24$

Subtracting 48 from both sides:

$6Q = 6P - 24$

Dividing every term by 6 simplifies the equation to:

$Q = P - 4 \quad (2)$

Solving P and Q Age Equations

We now have a system of two linear equations:

  1. $7P - Q = 46$
  2. $Q = P - 4$

We can use the substitution method. From equation (2), we can express $P$ in terms of $Q$ as $P = Q + 4$.

Substitute $P = Q + 4$ into equation (1):

$7(Q + 4) - Q = 46$

Distribute the 7:

$7Q + 28 - Q = 46$

Combine the terms involving $Q$:

$6Q + 28 = 46$

Isolate the $Q$ term by subtracting 28 from both sides:

$6Q = 46 - 28$

$6Q = 18$

Solve for $Q$ by dividing by 6:

$Q = \frac{18}{6}$

$Q = 3$

Age Calculation Verification

To ensure our answer is correct, let's verify it using the original conditions.

If $Q = 3$, then using $P = Q + 4$, we find $P = 3 + 4 = 7$. So, P is 7 years old and Q is 3 years old.

Verifying Condition 1:

Is $7 \times P$ equal to $Q + 46$? $7 \times 7 = 49$ $3 + 46 = 49$ Yes, $49 = 49$. Condition 1 holds true.

Verifying Condition 2:

After 8 years, P will be $7 + 8 = 15$ and Q will be $3 + 8 = 11$.

Is $6 \times (Q \text{'s future age})$ equal to $6 \times (P \text{'s future age}) - 24$? $6 \times 11 = 66$ $6 \times 15 - 24 = 90 - 24 = 66$ Yes, $66 = 66$. Condition 2 holds true.

Q's Present Age Found

Since both conditions are satisfied, the calculated present age of Q is correct.

The present age of Q is 3 years.

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Important Questions from Problem on Age

  1. 3 years ago, the father's age was 24 years more than twice his son's age. After how many years from now will his age be twice his son's age?
  2. If 4 times a son's age is added to his father's age, the sum is 100 years. If 2.5 times the father's age is added to the son's age, the sum is 97 years. What is the father's age (in years)?
  3. 3 years ago, the age of a father was 18 years more than twice his son's age. After how many years, from now, will he be twice his son's age?
  4. 8 years ago, the age of a father was 21 years more than twice his son's age. After how many years, from now, will he be twice his son's age?
  5. Two times the present age of P exceeds the present age of Q by 15 years. After 9 years, twice Q's age will be 14 years less than twice P's age at that time. What is the present age (in years) of Q?
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