Answer: 197,443,926,105,102,399,225,573,693
Step-by-step explanation:
Here we use combination which is the selection of all or part of a set of objects or items without considering the order of selection.
Mathematically, The number of 'r' combinations from 'n' elements is given as :
nCr = n!÷((n-r)!r!)
From the question above :
n=99 r=66
99C66 = 99!÷((99-66)!66!)
99!÷(33!66!) = 197,443,926,105,102,399,225,573,693
There are 197,443,926,105,102,399,225,573,693 different possible routes.