Try looking at the top of the wall. There are 5 bricks placed lengthwise.

Now look at the bricks directly below them.There are 3 bricks placed lengthwise and 3 bricks placed breadth-wise.

Notice that the total length of 5 bricks placed lengthwise is equal to the length of the 3 bricks lengthwise + 3 bricks breadthwise.

So when we compare them,each set has 3 lengthwise bricks in common.

Removing these, we realise that the 2 remaining bricks lengthwise is equal in length to the 3 remaining bricks breadthwise.

So 3 breadths = 6cm x 3 = 18cm = 2 lengths

1 length = 18cm ÷ 2 = 9cm


Now, we look one set of 4 bricks with the square hole in the middle.

Notice now that :

1 length of rectangle + 1 breadth of rectangle = 2 breadths of rectangle + 1 length of square hole

1 length + 1 breadth = 9cm + 6cm = 15cm

15cm = 2 breadths of rectangle + 1 length of square hole

To find 1 length of square hole, we subtract two breadths from 15cm

2 x 6cm = 12cm

So length of square hole =15cm - 12cm = 3cm

Area of 3 square holes
= 3 x 3cm x 3cm
= 3 x 9cm²
= 27cm²

In summary , the steps are :

3 x 6cm = 18cm

18cm ÷ 2 = 9cm

9cm + 6cm = 15cm

15cm - 6cm - 6cm = 3cm

3cm x 3cm x 3 = 27cm²