Algebra · real student question

Solve for X: 2400 = 2210 - (2000/180)(5/3)X.

Question

Solve for XX:

2400=2210(2000180)(53)X.2400=2210-\left(\frac{2000}{180}\right)\left(\frac53\right)X.

Step-by-step solution

  1. Simplify the coefficient before anything else. Reducing the first fraction by 2020:

    2000180=1009,\frac{2000}{180}=\frac{100}{9},

    and then multiplying by 53\tfrac53:

    100953=50027.\frac{100}{9}\cdot\frac53=\frac{500}{27}.

    Combining the two fractions into one now means only a single reciprocal has to be handled at the end.

  2. Rewrite the equation. It becomes

    2400=221050027X.2400=2210-\frac{500}{27}X.

    Before solving, predict the sign: the left side exceeds 22102210, so the subtracted term must be negative, which forces X<0X<0. Having that expectation makes a sign slip easy to catch.

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

    24002210=50027X    190=50027X.2400-2210=-\frac{500}{27}X\;\Longrightarrow\;190=-\frac{500}{27}X.

  4. Divide by the fractional coefficient. Dividing by 50027-\tfrac{500}{27} is multiplying by 27500-\tfrac{27}{500}:

    X=190(27500)=5130500=51350=10.26.X=190\cdot\left(-\frac{27}{500}\right)=-\frac{5130}{500}=-\frac{513}{50}=-10.26.

    The fraction reduces by 1010; note 513=27×19513=27\times19 and 50=2×5250=2\times5^{2} share no factor, so 51350-\tfrac{513}{50} is the exact value in lowest terms.

  5. Substitute back. With X=10.26X=-10.26:

    50027×(10.26)=190,2210(190)=2400.\frac{500}{27}\times(-10.26)=-190,\qquad 2210-(-190)=2400 ✓.

    The negative answer matches the sign prediction made in step 2.

Answer

X=51350=10.26X=-\frac{513}{50}=-10.26

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