Solve for x
x=100
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400-0.8x=420-x
Use the distributive property to multiply 0.8 by 500-x.
400-0.8x+x=420
Add x to both sides.
400+0.2x=420
Combine -0.8x and x to get 0.2x.
0.2x=420-400
Subtract 400 from both sides.
0.2x=20
Subtract 400 from 420 to get 20.
x=\frac{20}{0.2}
Divide both sides by 0.2.
x=\frac{200}{2}
Expand \frac{20}{0.2} by multiplying both numerator and the denominator by 10.
x=100
Divide 200 by 2 to get 100.
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