i) Using the binomial theorem you have
Equate the co-efficients of

on both sides using the above for

.
On the LHS we have
and on the RHS we want the co-efficients of

since we are dividing by

. The second binomial clearly does not have a co-efficient of

so we need only to find the required co-efficient of the first binomial, which is

.
ii) from i) set
This gives
Subtract 1 and note that

for all

.
This gives
Rewriting in sigma notation, we get:
Rewrite the binomial on the LHS:
Multiply both sides by

:
And rewrite the LHS:
(r-2)(r-3) = 24\left(\binom{m+5}{5} - 1\right))