First, multiply each side of the equation by #color(red)(6)# to eliminate the fractions and keep the equation balanced. #color(red)(6)# is the lowest common denominator of the two fractions and eliminating the fractions will make the problem easier to work.
#color(red)(6) xx 2/3 = color(red)(6) xx (z - 3)/2#
#12/3 = cancel(color(red)(6))3 xx (z - 3)/color(red)(cancel(color(black)(2)))#
#4 = 3z - 9#
Next, add #color(red)(9)# to each side of the equation to isolate the #z# term while keeping the equation balanced:
#4 + color(red)(9) = 3z - 9 + color(red)(9)#
#13 = 3z - 0#
#13 = 3z#
Now, divide each side of the equation by #color(red)(3)# to solve for #z# while keeping the equation balanced:
#13/color(red)(3) = (3z)/color(red)(3)#
#13/3 = (color(red)(cancel(color(black)(3)))z)/cancel(color(red)(3))#
#13/3 = z#
#z = 13/3#