Let the length and breadth of the rectangle be $$10$$ cm Area of rectangle = $$10 imes10=100$$ $$cm^2$$ After decreasing the length by 20%, => New length = $$10-(frac{20}{100} imes10)$$ = $$10-2=8$$ cm Similarly, new breadth = $$10-(frac{40}{100} imes10)$$ = $$10-4=6$$ cm => New area = $$8 imes6=48$$ $$cm^2$$ $$ herefore$$ Decrease in area = $$frac{(100-48)}{100} imes100=52\%$$ => Ans - (B)