Solve for r
r=4
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28+3r-10r=0
Subtract 10r from both sides.
28-7r=0
Combine 3r and -10r to get -7r.
-7r=-28
Subtract 28 from both sides. Anything subtracted from zero gives its negation.
r=\frac{-28}{-7}
Divide both sides by -7.
r=4
Divide -28 by -7 to get 4.
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