The graph shows a linear relationship between the amount of red dye, r, and the amount of yellow dye, y.
The rate of change of a line is the slope:
" slope " =( " change in " y)/( " change in " r)
From the graph, the line goes through the origin and rises steeply. A clear point on the line is approximately:
(2#9)
This means when the amount of red dye is 2gallons, the amount of yellow dye is 9gallons.
So the rate of change is:
9/2
That means for every 2gallons of red dye, the factory uses 9gallons of yellow dye.
The relationship can be written as:
y=9/2 r
So the correct interpretation is:
" The amount of yellow dye must be " 9/2 " of the amount of red dye. "
Therefore, the correct answer is:
# ( " A " )