Solve for x
x=35
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5x+7x=420
Multiply both sides of the equation by 35, the least common multiple of 7,5.
12x=420
Combine 5x and 7x to get 12x.
x=\frac{420}{12}
Divide both sides by 12.
x=35
Divide 420 by 12 to get 35.
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