The ratio of balls in a bag is as follows: 5 Green: 1 Yellow: 6 Black

How many balls would there be in the bag if you have 72 black balls?

The ratios are 5 Green / total, 1 yellow / total, 6 black / total

all together 5 + 1 + 6 = 12

6/12 = 1/2

so for every black ball, there is 1 other ball

if you have 72 black balls there are

2 x 72 balls = 144 balls