I am pretty sure that the which equations show that the set of whole numbers is not closed under subtraction are being revealed in options B.
1 – 2 = –1 and D.2 – 4 = –2
To determine which ones are correct, you have to find one that has whole numbers and not a whole in the end. After that the only thing you have to do is subtraction,and you will have the needed set of whole numbers.
Do hope it will help you!
