If the length of a rectangle is increased by 20% and its breadth is decreased by 10%, what is the percentage change in its area?

शुद्ध परिवर्तन = $x + y + (xy/100) = 20 - 10 + (20 * -10)/100 = 10 - 2 = 8\%$। चूंकि यह धनात्मक है, इसलिए क्षेत्रफल में 8% की वृद्धि होगी।