There is an inverse relationship between addition and subtraction.
This means that if an addition math fact is considered, for example 3 + 7 = 10,
then the following are also true:
Similar relationships exist for subtraction. The subtraction fact 10 - 3 = 7
has the inverse relationships:
The reason this is true is that these are equations. An equation
is balanced or the same on either side of the equals (=) sign.
If exactly the same thing is done to both sides of the equation, it will still
be balanced or equal.
This can be shown by starting with the equation 3 + 7 = 10:
- Subtract the same number from both sides 3 + 7 - 3 = 10 - 3
- On the left side the 3 and -3 produce 0 which leaves 7 = 10 - 3
- Turning the equation around to be in more normal form 10 - 3 = 7