Answer: 0.9 is the decreasing factor.
Explanation:
Here, The price of the ginger roots is G .
And, It there occurs the 10% off on this amount then,
The new price of the ginger is 90% of G.
That is, Final price of G =

=

= 0.9G
Since, 0.9 decreases the price of the ginger.
Therefore, It is called decreasing factor for the function which represents the price of the ginger.