yakiraz wrote:A) In a certain restaurant there are 4 different dressing. a customer can choose 0,1,2 or 3 different dressing. How many different dressing can a customer choose?

atlantic definitely has this right, above, and it's worthwhile understanding that method. You can also look at it this way: for each dressing, the customer has 2 choices: use it, or don't. So with no restrictions, the customer has 2^4 = 16 choices of dressing combinations. If he chooses 0, 1, 2 or 3 different dressings, he did not choose 4 different dressings, and there's only one way to choose all four dressings: say yes to everything. Thus there are 16 - 1 = 15 ways to choose 0, 1, 2 or 3.

yakiraz wrote: B) A, B, C, and X are prime consecutive positive numbers. what is A+B+C in terms of X.
1)4X+6
2)3X+12
3)3X+5
4)X^2
5)X

There are no equation-based formulas whatsoever in mathematics that relate any string of primes by addition. Indeed, there are many famous unsolved problems in math about the addition of primes: Goldbach's conjecture, for example. There is no way this question can contain the word 'prime'. My best guess is that the question means to talk about 'odd' numbers, not 'prime' numbers, and that the second answer choice is supposed to have a minus sign, not a plus sign. But that's just a guess. What's the source?