Algebra · real student question

Solve for x: 6.58x + 14 = 6.75x.

Question

Solve for xx:

6.58x+14=6.75x6.58x+14=6.75x

Step-by-step solution

  1. Recognise the shape. Two quantities grow at almost the same rate — 6.586.58 and 6.756.75 per unit — but one starts 1414 ahead. This is a break-even equation: it asks when the faster one catches up. Because the rates are close, expect a large answer.

  2. Collect the x terms on the side with the larger coefficient. Subtracting 6.58x6.58x from both sides keeps the remaining coefficient positive:

    14=6.75x6.58x14=6.75x-6.58x

  3. Subtract the decimals carefully. Aligning the hundredths:

    6.756.58=0.1714=0.17x6.75-6.58=0.17\qquad\Longrightarrow\qquad 14=0.17x

    That tiny 0.170.17 is the whole gap in growth rate, and it is what makes the answer large.

  4. Divide by 0.17.

    x=140.17=140017x=\frac{14}{0.17}=\frac{1400}{17}

    Multiplying numerator and denominator by 100100 clears the decimal, and 1717 is prime so the fraction is already reduced.

  5. Evaluate the decimal.

    x=140017=82.35294182.35x=\frac{1400}{17}=82.352941\ldots\approx82.35

    As a rough check, 0.17×82=13.940.17\times82=13.94, just under 1414 ✓.

  6. Verify in the original equation. Left: 6.58×82.352941+14=541.882353+14=555.8823536.58\times82.352941+14=541.882353+14=555.882353. Right: 6.75×82.352941=555.8823536.75\times82.352941=555.882353 ✓. Both sides agree to six decimals.

Answer

x=140.17=14001782.35x=\frac{14}{0.17}=\frac{1400}{17}\approx 82.35

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