Respuesta :
The formula for combinations is n! / (r!(n-r)!)
where n is the total number of objects and r is the sample.
So you get 6! / (2!(6-2)!)
The ! means you multiply the number by all numbers below it
so 6! = 6 * 5 *4 * 3 *2 *1 = 720
2! = 2*1 = 2
6-2 = 4, 4! = 4 * 3 *2 *1 = 24
Now you have 720 / 2 * 24 =
720 / 48
Answer = 15 possible combinations.