The formula for combination is
nCr = n!/(n - r)!r!
C represents the number of combinations
n represents the total number of objects to choose from
r represents the number of items selscted from n
From the information given,
n = 8 and r = 3
8C3 = 8!/(8 - 3)!3!
= 8! /5!3!
= 8 * 7 * 6 * 5 * 4 * 3!/5 * 4 * 3 * 2 * 1 * 3!
The 3! cancels out. It becomes
8 * 7 * 6 * 5 * 4 /5 * 4 * 3 * 2 * 1
= 6720/120
= 56
The answer is 56