16 ounces of dark chocolate. 2/5 of the chocolate was used to make frosting and the rest to make brownies. how much more chocolate did mrs. harrison using the brownies than in the frosting

16•2/5=6.4
6.4 ounces of chocolate for the frosting.
16-6.4=9.6
9.6 ounces of chocolate for the brownies.
9.6-6.4=3.2
3.2 ounces of chocolate for the brownies more than from the frosting.
(I hope I understood your question right. I don't have good English)

Think of it as five or above give it a shove. change the 5 or above to the right to a zero and add one to the number on the left.