Algebra · real student question

Boss is currently 8 times as old as Bew. In 8 years, Boss will be 3 times as old as Bew. How old is Boss now?

Question

Boss is currently 88 times as old as Bew. In 88 years, Boss will be 33 times as old as Bew. How old is Boss now?

Step-by-step solution

  1. Choose the smaller quantity as the variable. Let Bew's present age be xx years. Because Boss is 88 times as old now, Boss's present age is 8x8x. Naming the younger age keeps both expressions free of fractions at this stage.

  2. Age both people by the same amount. Eight years from now everyone is exactly 88 years older, so Bew is x+8x + 8 and Boss is 8x+88x + 8. A very common slip is to write Boss's future age as 8(x+8)8(x+8) — that would multiply the future ages by 8, which the problem never claims.

  3. Turn the future comparison into an equation. "Boss will be 3 times as old as Bew" means

    8x+8=3(x+8)8x + 8 = 3(x + 8)

  4. Solve the linear equation. Expand the right side and collect:

    8x+8=3x+245x=16x=165=3158x + 8 = 3x + 24 \quad\Longrightarrow\quad 5x = 16 \quad\Longrightarrow\quad x = \frac{16}{5} = 3\tfrac{1}{5}

  5. Answer the question that was asked. The problem wants Boss's age, not xx:

    8x=8165=1285=2535 years8x = 8 \cdot \frac{16}{5} = \frac{128}{5} = 25\tfrac{3}{5}\ \text{years}

  6. Check both conditions in the original wording. Now: 2535=8×31525\tfrac{3}{5} = 8 \times 3\tfrac{1}{5}, since 8×165=12858 \times \tfrac{16}{5} = \tfrac{128}{5}. In 8 years: Bew is 165+8=565\tfrac{16}{5} + 8 = \tfrac{56}{5} and Boss is 1285+8=1685\tfrac{128}{5} + 8 = \tfrac{168}{5}, and 3×565=16853 \times \tfrac{56}{5} = \tfrac{168}{5}. Both statements hold. The ages are not whole numbers, which is fine algebraically — the data simply were not chosen to give integer ages.

Answer

8x=1285=2535 years8x = \frac{128}{5} = 25\tfrac{3}{5}\ \text{years}

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