4700-3600=$1100 is the actual saving.
1100/4700=11/47 is the saving as a fraction of the original price.
11/47×100=23.4% approximately, converting the fraction into a percentage.
Another way to solve it is to first calculate 3600/4700=36/47.
Then convert to percentage: 36/47=0.766, 0.766×100=76.6%, which is a saving of 100-76.6=23.4% where 100% represents the original price of $4700.