First step, multiply each side of the equation by #color(red)(3)/color(blue)(4)# to eliminate the coefficient to the term in parenthesis and to keep the equation balanced:
#color(red)(3)/color(blue)(4) xx 4/3(7 - n) = color(red)(3)/color(blue)(4) xx 12#
#cancel(color(red)(3))/cancel(color(blue)(4)) xx color(blue)(cancel(color(black)(4)))/color(red)(cancel(color(black)(3)))(7 - n) = 36/4#
#7 - n = 9#
Next, subtract #color(red)(7)# from each side of the equation to isolate the #n# term while keeping the equation balanced:
#0 - n = 2#
#-n = 2#
Now, we can multiply each side of the equation by #color(red)(-1)# to solve for #n# while keeping the equation balanced:
#color(red)(-1) xx -n = color(red)(-1) xx 2#
#n = -2#
