7 times a number is the same as 12 more than 3 times a number

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7 times a number is the same as 12 more than 3 times a number

The phrase a number means an arbitrary variable, let's call it x.

Algebraic Expression 1:
7 times a number means we multiply 7 by x:
7x

Algebraic Expression 2:
3 times a number means we multiply 3 by x:
3x

12 more than 3 times a number means we add 12 to 3x:
3x + 12

The phrase is the same as means an equation, so we set 7x equal to 3x + 12
7x = 3x + 12 <-- Algebraic Expression