The Sum of three times a number and 18 is -39. Find the number

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The Sum of three times a number and 18 is -39. Find the number.

A number means an arbitrary variable, let us call it x.

Three times x:
3x

The sum of this and 18:
3x + 18

Is means equal to, so we set 3x + 18 = -39
3x + 18 = -39

Using our equation solver, we get x = -19