Find how much 20% is by setting up a proportion:
[tex] \frac{20}{100} = \frac{x}{19.5} [/tex]
Cross multiply:
[tex]100x = 390[/tex]
Divide both sides by 100 to isolate x:
[tex]x = 3.9[/tex]
Now because it says the new packaging contains 20% more, you add 3.9 ounces to 19.5 ounces.
[tex]3.9 + 19.5 = 23.4[/tex]
Your answer is 23.4 ounces.
