Solve for x
x=7
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21=3x
Variable x cannot be equal to 0 since division by zero is not defined. Multiply both sides of the equation by x.
3x=21
Swap sides so that all variable terms are on the left hand side.
x=\frac{21}{3}
Divide both sides by 3.
x=7
Divide 21 by 3 to get 7.
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