Question

a bag of concrate can be used to make a 5ft by 7ft porch.if you want to make a 20ft by 28ft,porch. how many bags of concreate do you need? the answer is not 4

Answer 1

Calculate the area of each rectangular:

5x7= 35sqft

20x28= 560sqft

If 1 bag makes 35sqft, 560sqft is how many bags;
This is how I write the equation;

1x bag 35sqft

X 560sqft

Solution: (560x1) : 35 = 16bags

I solved this based on my way of logic. I'd appreciate if you let me know if the answer is correct.

Answer 2

area of 5 x 7 porch = 5*7 = 35 sq. ft.

 area of 20 x 28 porch = 20 *28 = 560 sq. ft.

560 / 35 = 16

 so 16 bags are needed