Respuesta :

Answer:

8.4 cm^2

Step-by-step explanation:

The area of the rectangle is

A = lw

A = 3x *5x = 15x^2

126 = 15x^2

126/ 15 =15x^2/15

42/5 = x^2

We want to find the area of the square

A = l*w

A = x*x

A = x^2 = 42/5 = 8.4 cm^2