Question

If A + X = B + X, where X is a positive quantity, what can be said about A and B ?

Answer 1

From Euclid's axioms, we know,
"If equals are added to equals, the wholes are equal."

$\because$ X is an equal that has been added to A and B , and the wholes A+X and B+X are equal, it can be deduced that A and B are equal.