Solve for x
x=19
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21x-9=20x+10
Add -5 and 15 to get 10.
21x-9-20x=10
Subtract 20x from both sides.
x-9=10
Combine 21x and -20x to get x.
x=10+9
Add 9 to both sides.
x=19
Add 10 and 9 to get 19.
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