how can I calculate this NFYfrom 1 to N u F15360 N100 Y30 u3

how can I calculate this

NF/(Y+from 1 to N (u))

F=15360 N=100 Y=30 u=300

the answer is 25904 please explain that

NOTE: the 300 has the following answer in the book (0.2929) but i don know why

Solution

F=15360      N=100       Y=30        u=300

NF/(Y+sum from 1 to N(u))

100*15360/(30+sum from 1 th 100 (300))

as series of constant is constant sum from 1 th 100 (300)=300

=1536000/(30+300)

=4654.5454