Following the rule of PEDMAS
#1/2 - 1/3 xx 1/4 + 1/5 1/6 div 1/6#
#1/5 1/6 = 1/5 cdot 1/6# since there is no symbol attached!
Hence;
#1/2 - 1/3 xx 1/4 + 1/5 cdot 1/6 div 1/6#
#1/2 - 1/3 xx 1/4 + 1/5 xx 1/6 div 1/6#
So we'll take it step wise..
Since there are Parenthesis, Exponents.. we'll go to;
Division
#1/2 - 1/3 xx 1/4 + 1/5 xx color(red)(1/6 div 1/6)#
#1/2 - 1/3 xx 1/4 + 1/5 xx (color(red)(1/6 xx 6/1)) -> "Transposed!"#
#1/2 - 1/3 xx 1/4 + 1/5 xx color(red)(1/cancel6 xx cancel6/1)#
#1/2 - 1/3 xx 1/4 + 1/5 xx 1/1#
Multiplication
#1/2 - color(blue)(1/3 xx 1/4) + color(blue)(1/5 xx 1/1)#
#1/2 - 1/12 + 1/5#
Addition
#1/2 - color(orange)(1/12 + 1/5)#
Note, Addition and Subtraction deals with finding the LCM..
LCM of #12 and 5 = 60#
#1/2 - color(orange)((5 + 12)/60)#
#1/2 - 17/60#
Subtraction
#color(green)(1/2 - 17/60)#
LCM of #2 and 60 = 60#
#color(green)((30 - 17)/60)#
#13/60#