To determine how many drops of food coloring you need for 28 ounces of icing, you can set up a proportion based on the given ratio:
3 drops of food coloring / 7 ounces of icing = x drops of food coloring / 28 ounces of icing
Now, you can solve for x:
3/7 = x/28
To isolate x, cross-multiply and then divide:
3 * 28 = 7 * x
84 = 7x
Now, divide both sides by 7:
x = 84 / 7
x = 12
So, you would need 12 drops of food coloring for 28 ounces of icing.