Answer:
see below
Explanation:
The basic formula for this chart is ...
Percentage = Base × Rate
Dividing by Base or Rate gives two other versions of the same relation:
Rate = Percentage/Base
Base = Percentage/Rate
These are summarized in the chart at the second attachment. Covering one of the cells in the chart tells you how that cell is computed. (See the formulas above.)
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It is convenient to let a spreadsheet do the math. Unfortunately, for this problem there are three different formulas that need to be entered and copied to non-adjacent cells. Even so, IMO, it beats punching numbers on a calculator.