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Let the 3 consecutive multiples of 7 be 7, (7x + 7),(7x + 14)where x is a natural number.

As per the question,

7 + (7x + 7) + (7x + 14) = 357

⇒ 21x + 21 = 357

⇒ 21(x + 1) = 357

⇒ (divide both sides by 21)

⇒ x + 1 = 17

⇒ x = 17-1(transpose 1 to RHS)

Hence the smallest multiple of 7 is ,i.e. 112.