How do you evaluate #- ( 4x - 7) = 5x - ( 5x + 21)#?

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Answer 1 · 2017-09-14T10:30:46

See a solution process below:

First, remove all of the terms from parenthesis being careful to manage the signs of the individual terms correctly:

#-4x - (-7) = 5x - 5x - 21#

#-4x + 7 = 0 - 21#

#-4x + 7 = -21#

Next, subtract #color(red)(7)# from each side of the equation to isolate the #x# term while keeping the equation balanced:

#-4x + 7 - color(red)(7) = -21 - color(red)(7)#

#-4x + 0 = -28#

#-4x = -28#

Now, divide each side of the equation by #color(red)(-4)# to solve for #x# while keeping the equation balanced:

#(-4x)/color(red)(-4) = (-28)/color(red)(-4)#

#(color(red)(cancel(color(black)(-4)))x)/cancel(color(red)(-4)) = 7#

#x = 7#