Hello,

You can use this formula - [ x + y + (xy/100)]

Let X = Percentage Increase or Decrease in Length

Y = Percentage Increase or Decrease in Breadth

Use + plus or - minus sign according to increase or decrease.

So, according to question - there is 20% increase in length and 10% increase in breadth. Therefore X = +20, Y = +10

Now, put the values in the formula  [x + y + (xy/100)]

=  [ +20 + 10 + (+200/100)]

= [ 30 + 2 ] = 32%

Overall Increase in area of rectangle is 32%

Hope this was helpful.