Almond, Butter, Chocolate, Dough and Egg are 5 friends. They have to stand in a horizontal line. [I Like Mathematics]

12.

Here's a way of looking at it with very little math.

There are 5! ways of arranging 5 things. 5 * 4 * 3 * 2 * 1 = 120. Of those, one fifth have B on the left so, there are 120 / 5 = 24 possibilities to consider further.

Of these 24 arrangements of A, C, D and E, there are going to be 24 / 4 = 6 arrangements with each letter on the right. Since either C or D on the right satisfies the requirement and there are 6 of each, there are 12 arrangements in total that satisfy the requirements.