Answer : The concentration (v/v%) of food coloring in the test tube is 30%.
Solution : Given,
Drops of food coloring = 6 drops
Drops of water = 14 drops
Formula used :

Total drops in the test tube = Drops of food coloring + Drops of water
Total drops in the test tube = 6 + 14 = 20 drops
Now put all the given values in the above formula, we get

Therefore, the concentration (v/v%) of food coloring in the test tube is 30%.