x is a variable, while × is the symbol for multiplication.
(Pedantic note to mathematicians: for simplicity, the rules are phrased as equalities, but it is implied that they hold for all x. If a question read "6x + x = 7x", it means "6x + x ≡ 7x" or "6x + x = 7x ∀ x ϵ ℝ".)

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