First, subtract #color(red)(2)# from each side of the equation to isolate the #z# term while keeping the equation balanced:
#3 - color(red)(2) = 2 - color(red)(2) + 2/(z + 2)#
#1 = 0 + 2/(z + 2)#
#1 = 2/(z + 2)#
or
#1/1 = 2/(z + 2)#
Because both sides of the equation are pure fractions we can "flip" or invert the fractions without impact the solution:
#1/1 = (z + 2)/2#
#1 = (z + 2)/2#
Next, multiply each side of the equation by #color(red)(2)# to eliminate the fraction while keeping the equation balanced:
#color(red)(2) xx 1 = color(red)(2) xx (z + 2)/2#
#2 = cancel(color(red)(2)) xx (z + 2)/color(red)(cancel(color(black)(2)))#
#2 = z + 2#
Now, subtract #color(red)(2)# from each side of the equation to solve for #z# while keeping the equation balanced:
#2 - color(red)(2) = z + 2 - color(red)(2)#
#0 = z + 0#
#0 = z#
#z = 0#