Question 18393
if what you are asking is:
-63 divided by 21 divided by 5

it may be easier if you set it up like this:
(-63/21) / (5)

then look at it as two fractions:
-63/21 divided by 5/1 
(since any whole number may be written as having denominator  1)

to divide fractions, invert (flip upside down) the second fraction and multiply:
{{{-63/21}}} x {{{1/5}}}

so {{{(-63/21)}}}X{{{(1/5)}}}={{{-63/105}}} 
all that's left is simplifying, as needed