Algebra · real student question

Solve x - (x*0.8 - 5000)*0.03 = 7226 for x.

Question

Solve for xx:

x(0.8x5000)0.03=7226x-\left(0.8x-5000\right)\cdot 0.03=7226

Step-by-step solution

  1. Expand the bracket before touching the subtraction. Multiplying each term inside by 0.030.03:

    0.03(0.8x5000)=0.024x1500.03\left(0.8x-5000\right)=0.024x-150

    Doing this first means you only have to worry about one sign change, in the next step.

  2. Distribute the leading minus sign across both terms. This is where most sign errors happen: the minus applies to 150-150 as well, turning it into +150+150:

    x(0.024x150)=x0.024x+150x-\left(0.024x-150\right)=x-0.024x+150

    so the equation becomes

    0.976x+150=72260.976x+150=7226

  3. Isolate the xx-term. Subtract 150150 from both sides:

    0.976x=70760.976x=7076

  4. Divide by the coefficient.

    x=70760.976=7076000976=7250x=\frac{7076}{0.976}=\frac{7076000}{976}=7250

    The division is exact here — 0.976×7250=70760.976\times 7250=7076 with no rounding — which is a strong hint that 72267226 was chosen deliberately.

  5. Check in the original equation. With x=7250x=7250: 0.8(7250)=58000.8(7250)=5800, so 58005000=8005800-5000=800, and 0.03×800=240.03\times 800=24. Then 725024=7226 7250-24=7226\ \checkmark. Notice the check runs through the original bracket, not the expanded form, so it would also catch a distribution mistake.

Answer

x=7250x=7250

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