How do you solve $f+(-3)=-9$ ?

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Answer 1 · 2017-02-22T13:09:10

Add $color(red)(3)$ to each side of the equation to solve for $f$ while keeping the equation balanced:

$f + (-3) + color(red)(3) = -9 + color(red)(3)$

$f + 0 = -6$

$f = -6$

How do you solve f+(-3)=-9f+(-3)=-9?