A 23.4 ounce shampoo bottle is labeled "Now 30% more free!" and sells for $15.00. What is the price per ounce of the original bottle?
We need to know how many ounces are in the original bottle.
If x is the original amount, then x + .3x = 23.4 oz
1.3x = 23.4
x = 23.4\1.3 = 18 oz
The price per ounce is $15.00 / 18 oz = $0.84