The sum of a percentage of all items should be the same as a percentage of the sum, no?
Suppose you buy two items costing x and y, and there’s a constant sales tax of t (say 10%, or 0.1). You’d pay t * x + t * y, or t * (x + y). You can even generalize this to Σ(t * x) = t * Σx (for x ∈ X, where X is the set of prices you’re paying).
I think the issue they were bringing up though is that tax is not applied equally to all items, and that tax may be determined by number of items sold. I don’t actually know if this is true or not, but if it is, the distributive property doesn’t apply anymore. Edit: I re-read the comment, that doesn’t look like what they were saying actually. Either way, if tax is weird like this, distributive property may not apply anymore.
Suppose you buy two items costing
xandy, and there’s a constant sales tax oft(say 10%, or 0.1). You’d payt * x + t * y, ort * (x + y). You can even generalize this toΣ(t * x) = t * Σx(forx ∈ X, whereXis the set of prices you’re paying).In other words, yes.
In case you want the math name for this property, it’s the distributive property.
I think the issue they were bringing up though is that tax is not applied equally to all items, and that tax may be determined by number of items sold. I don’t actually know if this is true or not, but if it is, the distributive property doesn’t apply anymore.Edit: I re-read the comment, that doesn’t look like what they were saying actually. Either way, if tax is weird like this, distributive property may not apply anymore.