what we need to do is find the difference between the two numbers to find the difference in price and then figure out what the percent of 23.5 that is
23.50-18.80=4.7
now we'll set up a proportion
4.7 x
----- = -----
23.5 100
then cross multiply and divide
100×4.7=470/23.5=20
the percent of decrease is 20%
I hope I've helped!
