The formula for calculating the change between two values is:

#p = (N - O)/O*100# where #p# is the percent change, #N# is the New Value and #O# is the Old Value. In this problem we are give #p# (-60 - the suit was discount which means the change was negative_ and #N# (#$648#). We can substitute these into the formula and solve for #O#:

#-60 = (648 - O)/O*100#

#-60/100 = (648 - O)/O*100/100#

#-0.6 = (648 - O)/O*1#

#-0.6 = (648 - O)/O#

#O * -0.6 = O * (648 - O)/O#

#O * -0.6 = cancel(O) * (648 - O)/cancel(O)#

#-0.6O = 648 - O#

#-0.6O + O = 648 - O + O#

#(1 - 0.6)O = 648#

#0.4 O = 648#

#(0.4 O)/0.4 = 648/0.4#

#O = 1620#