$3.00. boxes of shablam! cereal originally cost the store has reduced the price by 25%. you have a coupon for an additional 20% off the already discounted price. what is the final price of the cereal?

A discount of 25% means you're paying (100% -25%) = 75% of the original price. An additional discount of 20% means you're paying (100% -20%) = 80% of the discounted price. In the end, you're paying
  $3.00*75%*80% = $1.80

The final price of the cereal is $1.80.

The density of the cube is 40