Algebra · real student question

Solve for x: x = (500000 - 100000 - 50000 - x) x 12%.

Question

Solve for xx:

x=(50000010000050000x)×12%.x=(500000-100000-50000-x)\times 12\%.

Step-by-step solution

  1. Convert the percentage to a decimal. A percentage is a fraction with denominator 100100, so

    12%=12100=0.12,12\%=\frac{12}{100}=0.12,

    and the equation becomes

    x=(50000010000050000x)×0.12.x=(500000-100000-50000-x)\times 0.12.

    Leaving the %\% sign in place while doing algebra is the fastest way to lose a factor of 100100.

  2. Simplify the known part of the bracket. The three constants combine independently of xx:

    50000010000050000=350000,500000-100000-50000=350000,

    so

    x=0.12(350000x).x=0.12\,(350000-x).

    Notice that xx appears on both sides — this is a self-referential equation (the kind that shows up when a fee is a percentage of what is left after the fee), not a one-step arithmetic problem.

  3. Expand the right-hand side. Distributing the 0.120.12 over both terms:

    x=0.12×3500000.12x=420000.12x.x=0.12\times 350000-0.12x=42000-0.12x.

    Check the product: 350000×0.12=350000×12100=3500×12=42000350000\times 0.12=350000\times\tfrac{12}{100}=3500\times 12=42000 ✓.

  4. Collect the xx terms and divide. Adding 0.12x0.12x to both sides gathers the unknown on the left:

    x+0.12x=42000    1.12x=42000    x=420001.12=37500.x+0.12x=42000\;\Longrightarrow\;1.12x=42000\;\Longrightarrow\;x=\frac{42000}{1.12}=37500.

    The coefficient 1.121.12 — not 0.880.88 — is what makes this different from "12% of 350000"; the answer 3750037500 is genuinely smaller than 4200042000.

  5. Substitute back into the original statement. The bracket becomes 35000037500=312500350000-37500=312500, and

    312500×0.12=37500.312500\times 0.12=37500 ✓.

    The consistency check is worth doing precisely because self-referential equations are easy to set up backwards.

Answer

x=420001.12=37500x=\frac{42000}{1.12}=37500

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