Solve for x
x=70
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7x+5x=840
Multiply both sides of the equation by 35, the least common multiple of 5,7.
12x=840
Combine 7x and 5x to get 12x.
x=\frac{840}{12}
Divide both sides by 12.
x=70
Divide 840 by 12 to get 70.
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