It’s 4 because y is a variable plus any number in front of a variable makes it a coefficient
Take the area of the small photograph and divide it by four, assuming it's a square, each side would then be 6 inches. The large photograph has double the side length of the small one, so 6 multiplied by 2 is 12. To find the area of the large (square) photograph, multiply 12 by 12 as two of the sides, and the area of the large photo is 144 square inches
Or a subset of the natural numbers.