Question

Please answer this question with steps

Answer 1

Perimeter of rectangle = 20 cm
⇒2( l+b) = 20 cm
⇒ l+b = 10 cm
⇒  l = (10-b) cm
Now, 
Area of rectangle = 21 cm²
⇒ l×b = 21 cm²
⇒(10-b)×b = 21 cm²
⇒ b² - 10b +21 = 0
∴ b = 7 cm  OR b = 3 cm
then, l = 3cm OR l = 7 cm
Now, 
The side of the square= a  = 7cm - 3 cm
                                             = 4 cm
∴ Perimeter of the square = 4a
                                            = 4 × 4cm
                                            = 16 cm
The perimeter of the square formed in middle is 16 cm (Option B)

I hope this helps you ^_^