Final answer:
The phrase '15 less than a number m' translates to the algebraic expression m - 15, which indicates the subtraction of 15 from the variable m.
Step-by-step explanation:
The phrase "15 less than a number m" is an algebraic expression that can be represented by the expression m - 15. It essentially means that you start with a variable, in this case, m, which stands for an unknown number, and then you subtract 15 from it.
Therefore, the phrase is mathematically translated to taking away 15 from m, leaving us with an expression that can be used in various mathematical contexts, such as solving equations or evaluating expressions.