What are the rules in subtraction?

Answer 1

Subtraction without signed numbers:

If the first number is less then the next the answer becomes negative,and is still subtracted.

If the first number is greater then the next it is positive.

In arithmetic, subtraction is one of the four basic binary operations; it is the inverse of addition, meaning that if we start with any number and add any number and then subtract the same number we added, we return to the number we started with. Subtraction is denoted by a minus sign in infix notation, in contrast to the use of the plus sign for addition.

Since subtraction is not a commutative operator, the two operands are named. The traditional names for the parts of the formula c − b = a

are minuend (c) − subtrahend (b) = difference (a).

Subtraction is used to model four related processes:

1. From a given collection, take away (subtract) a given number of objects. For example, 5 apples minus 2 apples leaves 3 apples.
2. From a given measurement, take away a quantity measured in the same units. If I weigh 200 pounds, and lose 10 pounds, then I weigh 200 − 10 = 190 pounds.
3. Compare two like quantities to find the difference between them. For example, the difference between $800 and $600 is $800 − $600 = $200. Also known as comparative subtraction.
4. To find the distance between two locations at a fixed distance from starting point. For example if, on a given highway, you see a mileage marker that says 150 miles and later see a mileage marker that says 160 miles, you have traveled 160 − 150 = 10 miles.

Additional Information:-

A double negative becomes a plus as for example: 6-2 = 4 but 6--2 = 8