Subtraction
= Subtraction
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Subtraction adds the <additive inverse>: $a-b=a+(-b)$. On the <number line>, $2-3=-1$ is a shift three units left from $2$. Reversing the two inputs changes the sign: $3-2=1$, so <subtraction> is generally not <commutative>. Solving $x+3=2$ gives the same answer $x=-1$ by adding $-3$ to both sides; the operation preserves equality while undoing the added amount.