Solve for r
r=-16
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\frac{6.4}{-0.4}=r
Divide both sides by -0.4.
\frac{64}{-4}=r
Expand \frac{6.4}{-0.4} by multiplying both numerator and the denominator by 10.
-16=r
Divide 64 by -4 to get -16.
r=-16
Swap sides so that all variable terms are on the left hand side.
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