Unclear When an equal amount is taken from equals an equal amount results This example axiom is unclear what does taken mean I can see only two interpretations 1 Subtracting equal amounts from equals produces equal amounts then the quote should be revised to read equal amounts result as there are two quantities being compared 2 Subtracting equal amounts from two quantities and adding each to a third produces an amount equal to the first two this is plainly false So perhaps the quote should be revised