well first expand out the right term

$(2c+5d) \displaystyle \sum_{k=0}^{14} \binom{14}{k} c^k d^{14-k}$

now do the multiplication

$\displaystyle 2\sum_{k=0}^{14}\binom{14}{k} c^{k+1} d^{14-k} +

5\displaystyle \sum_{k=0}^{14}\binom{14}{k} c^k d^{14-k+1}$

grab the $c^4 d^{11}$ coefficents from each sum

$\displaystyle 2 \binom{14}{3} + 5 \binom{14}{4}$

and I leave you to evaluate that last expression