Algebra · real student question

Solve for x: x - ((36000 + x) - 35000) * 0.03 - 180 = 6500.

Question

Solve for xx:

x((36000+x)35000)0.03180=6500x-\left((36000+x)-35000\right)\cdot 0.03-180=6500

Step-by-step solution

  1. Collapse the nested brackets first. The inner expression contains only constants and one xx:

    (36000+x)35000=x+1000(36000+x)-35000=x+1000

    so the equation becomes

    x0.03(x+1000)180=6500x-0.03(x+1000)-180=6500

    Doing this before distributing keeps the 0.030.03 from being multiplied across three terms instead of two.

  2. Distribute the 0.03-0.03 across both terms.

    x0.03x30180=6500x-0.03x-30-180=6500

    Note 0.03×1000=300.03\times 1000=30, and it is subtracted because the whole bracket is subtracted.

  3. Combine like terms on the left. The xx terms give 10.03=0.971-0.03=0.97, and the constants give 30180=210-30-180=-210:

    0.97x210=65000.97x-210=6500

    The coefficient 0.970.97 is the readable meaning of the problem: 3%3\% of the excess is taken away, so 97%97\% of xx survives.

  4. Isolate the xx term. Add 210210 to both sides:

    0.97x=67100.97x=6710

  5. Divide by 0.970.97 carefully.

    x=67100.97=67100097=6917.52586917.53x=\frac{6710}{0.97}=\frac{671000}{97}=6917.5258\ldots\approx 6917.53

    Converting to the exact fraction 67100097\tfrac{671000}{97} before dividing is the safest way to get the digits right; the nearby wrong value 6918.566918.56 comes from a single mis-carried digit in the long division.

  6. Check by substituting back. With x=6917.5258x=6917.5258: the bracket is 7917.52587917.5258, times 0.030.03 is 237.5258237.5258, so the left side is 6917.5258237.5258180=6500.00006917.5258-237.5258-180=6500.0000 ✓. (Using 6918.55676918.5567 instead would give 6501.006501.00, one whole unit off.)

Answer

x=671000976917.53x=\frac{671000}{97}\approx 6917.53

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