For any numbers \(a\) and \(b\),

if

$$\large{a = b}$$

then

$$\large{b = a}$$

**In words:** If one element is equal to a second element, then the second element is equal to the first element.

Examples:

If \(7 = 3 + 4\), then \(3+4 = 7\)

If \(xy = 2\), then \(2 = xy\)

If \(x + y = y + x\), then \(y + x = x + y\)