In the book of CBSE, NCERT Class7, there is a problem which I cannot understand. It is present on Pg.210, Try These. Can anyone explain it please?  

In the said problem i am providing you the solution of first 3 parts as:

It is given that the length of rectangle is 6 cm and breadth is 4 cm.

So, area of each rectangle = 6 cm × 4 cm = 24 cm²

(a)   

From the above figure, it is quite clear that the rectangle of dimension 6 cm × 4 cm is divided into 6 congruent parts.

Therefore, area of 6 congruent parts =  area of large rectangle

⇒ area of 1 congruent parts = 24 cm²/6 = 4 cm²

(b)

Here, from the above figure, it is quite clear that the rectangle of dimension 6 cm × 4 cm is divided into 4 congruent parts.

Therefore, area of 4 congruent parts =  area of large rectangle

⇒ area of 1 congruent parts = 24 cm²/4 = 6 cm²

(c)

Again, from the above figure, it is quite clear that the rectangle of dimension 6 cm × 4 cm is divided into 2 congruent inverse parts.

Therefore, area of 2 congruent parts =  area of large rectangle

⇒ area of 1 congruent parts = 24 cm²/2 = 12 cm²

Similarly, find the number of congruent part in other two remaining figures and try to find the area of each part.

Hope you get it!!