the dimensions of the original rectangle
length - L
width - W
area = L*W = LW
after the modification, new dimensions are
length increased by 30 %
Length = L * 1.3 = 1.3L
Width = W * 0.6 = 0.6W
new area = 1.3L * 0.6W
= 0.78LW
the percent decrease in area
decrease % = (difference in area)/original area * 100
= (LW - 0.78LW)/LW * 100
= 0.22LW/LW * 100
= 22%
percent decrease is 22%