Solve for x
x=80
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3x+8\left(140-x\right)=720
Multiply both sides of the equation by 48, the least common multiple of 16,6.
3x+1120-8x=720
Use the distributive property to multiply 8 by 140-x.
-5x+1120=720
Combine 3x and -8x to get -5x.
-5x=720-1120
Subtract 1120 from both sides.
-5x=-400
Subtract 1120 from 720 to get -400.
x=\frac{-400}{-5}
Divide both sides by -5.
x=80
Divide -400 by -5 to get 80.
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