A double decker bus can accommodate 75  passengers 35 in the lower deck 40 in the upper deck. The number of ways the passengers can be accommodated if 5 want to sit only in lower deck and 8 want to sit only in upper deck is 

Total no of seats in upper deck = 40

Total no of seats in lower deck = 35

Since 5 want to sit in lower, 8 want to sit in upper.

Remaining seats in lower deck = 30

Remaining seats in upper deck = 32

So Remaining 62 persons are to be divided into 2 groups containing 30, 32 in ⁶² ${\mathrm{C}}_{30}$ ways.