I think it’s C sorry if I’m wrong
Answer:
Distributive Property
Step-by-step explanation:

Step-by-step explanation:
Distance = rate × time
If B is the rate of the boat, and C is the rate of the current, then we can write two equations:
18 = (B + C) × 3
18 = (B − C) × 9
Simplifying the equations:
6 = B + C
2 = B − C
Add the equations together to eliminate C:
8 = 2B
B = 4
Plug into either equation to find C:
C = 2
The boat's rate is 4 mph, and the current's rate is 2 mph.
When expanding number, we should separate the numbers according to the places like the number 275 written in expanded form 200+70+5. So, in this question we must likely done like this. The number is 39,005 the sum that is written on expanded form is 30,000+9,000+5.