1. The problem states that 3 times a number $f$ equals 15, or mathematically, $3f=15$. 2. To find the value of $f$, divide both sides of the equation by 3 to isolate $f$: $$f=\frac{15}{3}$$ 3. Simplify the right side: $$f=5$$ 4. Therefore, the value of $f$ is 5.