I think you are missing part of the problem. If you had another equation or a value for x you could solve it.
Answer:
I believe it’s the 3rd one.
Explanation:
It’s the only graph where it looks like (2.5,5) was graphed.
Answer:
I am not sure but I think the correct answer is c
Answer: 
Step-by-step explanation:
Given : Two opposite sides of a rectangle are each of length x.
Let the other adjacent side be y.
The perimeter of the rectangle is 12 units.
Perimeter of rectangle is given by :-

The area of rectangle is given by :-

Hence, the area as a function x = 
The problem is 3+6x = 15 with x being the number of white numbers.
Isolate variable by subtracting 3 on both sides: 6x = 12.
Isolate variable by dividing 6 on both sides: x = 2
The number of white marbles is 2.