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
