answer will be n.

since 13 is remainder in 1st case, so d >13.

but 3n is multiple of n ( here i assumed n to be +ive integer).

also d>9 as per 2nd one.

from 1st no. is odd ( 3n) and from 2nd no. is even (4n) hence , if n=1, then remainder must be 1, if n=2 then remainder must be 2 and so on, hence n should atleast be 27 ( since d>13) , which is also multiple of 3, i.e. n=9 but 4n=36 does not give remainder =9 hence this value is neglected. , hence above both are satisfied if we take n=21 and d=25, which satisfies all i.e.

3n/d=63/25=13 remainder

4n/d=84/25=9 remainder

n/d=21/25= smaller value shall be remainder, i.e. 21. i.e. n. hence done.