Algebra · real student question

Solve for X: 600 = 2210 - (2000/180)(5/3)X.

Question

Solve for XX:

600=2210(2000180)(53)X.600=2210-\left(\frac{2000}{180}\right)\left(\frac53\right)X.

Step-by-step solution

  1. Combine the two fractions into a single coefficient. Reduce the first fraction by dividing top and bottom by 2020, then multiply:

    2000180=1009,100953=50027.\frac{2000}{180}=\frac{100}{9},\qquad \frac{100}{9}\cdot\frac53=\frac{500}{27}.

    Simplifying before multiplying keeps the numbers small; multiplying first would give 10000540\frac{10000}{540}, the same value with more to reduce.

  2. Predict the sign of the answer. The equation reads 600=221050027X600=2210-\frac{500}{27}X. Since 600600 is less than 22102210, the subtracted term must be positive, so X>0X>0. (In the companion problem where the left side is 24002400, the same reasoning forces X<0X<0.)

  3. Isolate the XX term. Subtracting 22102210 from both sides:

    6002210=50027X    1610=50027X.600-2210=-\frac{500}{27}X\;\Longrightarrow\;-1610=-\frac{500}{27}X.

    Both sides are negative, which is consistent with the sign prediction.

  4. Divide by the fractional coefficient. Multiplying by the reciprocal 27500-\tfrac{27}{500}:

    X=(1610)(27500)=43470500=434750=86.94.X=(-1610)\left(-\frac{27}{500}\right)=\frac{43470}{500}=\frac{4347}{50}=86.94.

    The fraction reduces by 1010; since 4347=34×53.674347=3^{4}\times 53.67\ldots shares no factor with 50=2×5250=2\times5^{2}, 434750\tfrac{4347}{50} is in lowest terms.

  5. Substitute back to confirm. With X=434750X=\tfrac{4347}{50},

    50027×434750=1610,22101610=600.\frac{500}{27}\times\frac{4347}{50}=1610,\qquad 2210-1610=600 ✓.

    The positive answer matches the sign prediction from step 2.

Answer

X=434750=86.94X=\frac{4347}{50}=86.94

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