twelve less than the product of three and a number is less than 21

Question

the question is and algebra question

Answer 1

First convert the question into algebraic notation.  So you have twelve less than the product of three and a number.  The product of three and a number (that is, a variable) can be symbolized as 3x, and twelve less than that is 3x - 12 and this expression is less than 21 so that the whole thing comes out to 3x - 12 < 21 and this last inequality can be solved in the usual way.

 

3x - 12 < 21

3x < 33

x < 11