Question

What is 3.5% of 12.90?

Answer 1

Consider this as fractions:
`(100%)/(3.5%)=12.90/x` where `x` (what you are looking for) is a fraction of `12.9` as `3.5` is a fraction of `100`. The two fractions must give you the same result!
so rearranging:
`x=(3.5%)/(100%)*12.90=0.035*12.90=0.451`

Hope it is not confusing...