If the length of a rectangle is increased by 120 %, and its width is decreased by 20%,
what happens to the area of the rectangle?

Let length of rectangle=x and width be y
.`. area=x*y
now new length=x+12x/10=22x/10
width=y-y/5=4y/5
now
new area=new length-new width=22x/10*4y/5
new area=88xy/50

The area of the rectangle will decrease because lets say the length is 2 and the width is 1
originally the area of the rectangle is lxw which is 2x1 is 2. But if we increase the length by 120% which will be 2.4 and increase the width decreased by 20% which is 0.8 then if we multiply them using the formula its 1.92 which decreased