There are r red ball, b blue ball and w white ball in a bag. What is the ratio of the number of blue ball to the total no. of ball in terms of r, b and w.?  Pick one.
A) r / (r + b + w)
B) (r + b + w)
C) r * (r + b + w)
D) (r + b + w)/r
E) None
The total number of marbles is   r + b + w   The total ratio of blue marbles to the total number of marbles is   r / (r + b + w)   r / (r + b + w)
<result>A</result>
There are r red ball, b blue ball and w white ball in a bag. What is the ratio of the number of blue ball to the total no. of ball in terms of r, b and w.?