Answer:
the different pairs will result from selecting two different brands at a time = 20 pairs
Explanation:
Let's call the 5 brands; A, B, C, D, E
Now, these 5 brands are paired together.
Thus, we will use the Permutation method which is P(n, r) = n! / (n - r)!
So, the different pairs will result from selecting two different brands at a time would be;
P(5, 2) = 5! / (5 - 2)!
This gives; (5 x 4 x 3 x 2 x 1)/(3 x 2 x 1) = 20