the opposite of a sum is the difference
If we define "opposite" as the additive inverse, the sum is zero.
Zero
Other opposites of short include: lengthy (in time) sufficient (in quantity)
Opposite sides of a dice add up to 7
Quantity has no opposite.
the opposite of a sum is the difference
If the opposite is meant to be the additive opposite and not the multiplicative opposite, then their sum is zero. The reason is that is what defines an additive opposite!
You can calculate quantity in Excel with the SUM function.
The opposite of most (greatest in quantity or extent) is least.
The opposite of most (greatest in quantity or extent) is least.
When you add zero to any quantity, the sum is the original quantity.
An amount is a quantity of something, a total, or sum.
An amount is a quantity of something, a total, or sum.
A trapezoid (not tapezoid!) is a plane shape. It has no quantity associated with it so there is no "sum of a trapezoid".
If by "opposite" you mean "additive inverse", the sum is zero. For example, 5 + (-5) = 0.
Light as in the opposite of dark? Then it would be "Sum lux." "Ego sum lux" is also appropriate. Light as in the opposite of heavy? Then it would be "Sum levis" (or "Ego sum levis)."