Can somebody help me with these two math problems

You have two cards with a sum of -12 in both hands. a. what two cards could you have? b. you add two more cards to your hand, but the total sum if the cards remains the same, (-12).

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.

At a kentucky friend chicken, a survey showed 2/3 of all people preferred skinless chicken over the regular chicken. if 2,400 people responded to the survey, how many people preferred regular chicken?