I'm taking a math theory class and am in over my head. I'm making it but am completely stumped by this question. "Jill asks each of her classmates to choose a number, then multiply the number by -3, add 2 to the product, multiply the result by -2, and then subtract 14. Finally, each student is asked to divide the result by 6 and record the answer. When Jill gets their answers, she adds 3 to it in her head and announces the number that classmate originally chose. How did Jill know to add 3 to ach answer?"

Can anyone help?