Explain what you need to do with the decimals when adding or subtracting with decimals?

You need to line up the numbers so the decimal points are aligned. If there are more decimal places for example let’s say 3.14+3.861 you would add them together but put 3.14 as 3.140 so the 1 in 3.861 has a place to go. By the way the answer is 7.001. When subtracting decimals you would do the same thing. For example 6.59-2.418 you would subtract the same way as you would with whole numbers just with decimals. So make 6.59 6.58 with 10 in the thousandths place. A bit confusing but it takes time to understand the concept. So practice! The answer would be 4.172. Hope this helps!

No he does not because he can only cover 12 square feet from 15 square feet which he will still need 3 more. this is because if 3×5=15 square feet and 15-12=3 which thats the answer