Respuesta :
The number of square feet of their backyard will NOT be taken up by the pool should be 100 square feet.
Calculation of the number of square feet;
Since 1 centimeter represents 5 feet. 4 cm 6 cm And, the area of the Hamiltons' backyard is 900 square feet.
So here it can be like
4cm (5) = 20ft
6cm (5) = 40ft
Now
20ft : 40ft pool
20(40) = 800 square ft
So,
= 900sq ft - 800sq ft
= 100 square feet
Learn more about area here: https://brainly.com/question/17758676