Final answer:
If y were a negative number, x would be positive in the expression x = -4y because the product of two negative numbers is positive.
Step-by-step explanation:
In the expression x = -4y, if y were a negative number, the value of x would be positive. This is because when you multiply two negative numbers, the answer has a positive sign. For instance, if y were -2, then x would be 8 since -4 multiplied by -2 equals 8.
This relationship where a negative multiplied by a negative equals a positive is a basic rule in multiplication, and it is consistent regardless of the magnitudes of the numbers involved.