#-2/3z = -6#
Reverse
#z = -\frac{6}{-\frac{2}{3}}#
#--\frac{6}{-\frac{2}{3}} = \frac{6}{-\frac{2}{3}}#
#"Apply the fraction rule"\quad \frac{a}{-b}=-\frac{a}{b}#
#\frac{6}{-\frac{2}{3}} = -\frac{6}{\frac{2}{3}}#
#\"Apply the fraction rule":\quad \frac{a}{\frac{b}{c}}=\frac{a\c}{b}#
#-\frac{6}{\frac{2}{3}}# = #-"3 * 6"/2 = -18/2#
= #-(-18/2)#
= #-(-9)#
=# +9#