Goodwill please solve...

Shubham kumar (.) (620 Points)

12 December 2012  
Goodwill of a firm of A and B is valued at Rs.45000. It is appearing in the book at Rs.15000. C is admitted for 1/4Th share. The Amount of goodwill, which she is supposed to bring will be. . . . . . Answer is Rs.11,250. Please explain it.