Question 1085452
It really does not matter what the monetary unit or the original cost is,
so we can calculate based on an assumed original cost of 100 peculiar (a made up money unit).
If the original cost was 100,
a 20% increase would bring it up to 100+20=120.
After that a decrease of 30% would reduce the cost to
70% = {{{70/100=7/10=0.7}}} of 12p0.
That is {{{0.7*120=84}}} .
A decrease from 100 to 84 is a decrease of
100-84=16.
A decrease of 16 from 100 is a 16% decrease.