I have a bag containing red, green, blue, and white marbles and the ratio red:green:bue:white is 2:2:5:7. I have 320 marbles. How many blue marbles do I have?
BLUE are 5 out of (2+2+5+7) = 5 / 16 of 320
5/16 * 320 = ........
+36915 
