No, it is impossible. Intuitively, a negative number sits at the left of 0 on the number line, and a positive number sits at the right of 0 on the number line. And a number x is greater than another number y if x sits at the right of y on the number line. So, every positive number is greater than any negative number.
Also, by definition, a positive number is greater than 0, and a negative number is smaller than zero. So, if x is positive and y is negative, you have

and since the relation of order "<" is transitive, this implies

Y = -3x + 14
Subtracted 3x from both sides
Answer: 30 buttons
Step-by-step explanation:
If there were 8 kids, and 7 more joined, then there were 15 kids making snowmen (8+7 = 15). Each child used 2 buttons for the eyes, so 30 buttons were used (15 x2 = 30). This is assuming no other buttons were used on the snowmen for anything else