There is no need to change the sign greater than or less than when adding and subtracting, because the addition and subtraction shift term is equivalent to the addition or subtraction of the number of items to be moved at the same time on both sides, while the multiplication and division shift term is the multiplication or division of the number of items to be moved at the same time on both sides, so in multiplication and division, if the displacement term is positive, there is no need to change the sign, and if the displacement term is negative, it needs to change the sign. (Because if it is a negative number, you will change the original size relationship between the two sides when you move the item: positive number is greater than negative number)

Just count it. No sign. Because: factor × factor = product, so factor = product/factor. The law of subtraction: minuend-subtraction = difference, that is, minuend = difference+subtraction.