if you first find that what is the percentage of $60 in $72 then you can find the percent decrease in price so you should say:
?/100 = 60/72
so ? is your percentage:
60*100/72 = 83.34
so the percent that decrease in price will be:
100 - 83.34 = 16.66 :)))
i hope this is helpful
have a nice day