Solve for x
x=-10
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3x-40-7x=0
Subtract 7x from both sides.
-4x-40=0
Combine 3x and -7x to get -4x.
-4x=40
Add 40 to both sides. Anything plus zero gives itself.
x=\frac{40}{-4}
Divide both sides by -4.
x=-10
Divide 40 by -4 to get -10.
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