Question 299263

 Let the length of the rectangle = x
 So, the breadth of the rectangle = (x/3)+5

 Area = length * breadth.=> 42 Sq.mtr.
      =  x * [(x/3) + 5] =  42 Sq.mtrs.
      =  x^2/3 + 5x = 42 Sq.mtrs.
      =  x^2/3 + 5x - 42 = 0  .........  ( 1 ). Now Eqn.1 * 3, we get
      =  x^2 + 15x - 126 = 0  .........  ( 2 )
      =  (x + 21)(x - 6) = 0  So either (x+21) or (x-6) = 0
      If x+21 = 0, then x=-21 whereas the length cannot be negative.  So, 
      x = 6.  [(x/3)+5] = 7.
      Length of the rectangle = 6 mtrs.; breadth = 7 mtr.;

      I hope this is clear to you.  All the best.  Feel free to contact me if you have doubts in maths.

gsm