Abag of concrete equals 1000 cu. inches. your customer already has 2 bags at home. how many more bags does he need to fill an area of 5’ x 10” x 10”?

From the information given;
1 bag of concrete = 1000 in^3
2 bags at home = 1000*2 = 2000 in^3

The available space has a volume of;

Volume = (5*12)*10*10 (Note: 1 ft = 12 inches)
Volume = 60*10*10 = 6000 in^3

The remaining volume = Available space - occupied space = 6000 - 2000 = 4000 in^2

1 bag = 1000 in^3
x bags = 4000 in^2

Then,
x = 1*4000/1000 = 4 bags.
This means 4 more bags of concrete will be required to fully fill the  space.