1. The problem asks: How do you find the function of a problem? 2. A function in mathematics is a relation that assigns exactly one output to each input. 3. To find or define a function from a problem, you first identify the input variable(s) and the output variable. 4. Then, determine the rule or formula that connects the input to the output. 5. This rule can be expressed as an equation like $y = f(x)$, where $x$ is the input and $y$ is the output. 6. For example, if the problem states "the output is twice the input plus three," the function is $f(x) = 2x + 3$. 7. Important rules: each input must have exactly one output; if multiple outputs exist for one input, it is not a function. 8. To verify a function, check that for every input value, the output is unique. 9. In summary, find the variables, understand their relationship, and write the formula that maps inputs to outputs.