Question

The square is divided into 3 parts.

Answer 1

The total whole number area of the square = 1.

Part A + Part B + Part C = 1.

1/3  +  2/5 + C  = 1.

(5+ 6)/15 +    C  = 1.    LCM of 3 and 5 is 15.

11/15 + C = 1.

C =  1/1 - 11/15   = (15 -11)/15

C = 4/15.

Cheers. 

Answer 2

1/3= 5/15
2/5= 6/15

5/15 + 6/15 = 11/15

15/15 - 11/15 = 4/15

Part C= 4/15