How do you add #-9/8+7/4#?
WE have denominators
Size indicator is how many of what you are counting to make a whole 1 of something.
We need to add/subtract counts but we can only do this 'directly' if the 'size indicators' (denominators) are the same.
Multiply by 1 and you do not change the intrinsic value. However, 1 comes in many forms. So we can change the way something looks but not change its intrinsic value.
Change the order:
This is the same in value as:
But write 1 as