6n-7+(7+25(6n-7))/6
(25*6n-168)/6=25n-28

6k-31t=7
k=(7+31t)/6=5t+(t+7)/6
t+7=6n
t=6n-7
6k-7=31t
6k=31t+7=31(6n-7)+7=31*6n-210
k=31n-35

解答のk=31n+27のnに
n-1を代入k=31n-4
n-2を代入k=31n-35