1. The problem is to simplify the expression: $\frac{X - 20}{2} \times B$. 2. The formula used here is the order of operations (PEMDAS/BODMAS), which tells us to perform division and multiplication from left to right. 3. First, divide $X - 20$ by 2: $$\frac{X - 20}{2}$$. 4. Then multiply the result by $B$: $$\left(\frac{X - 20}{2}\right) \times B = \frac{(X - 20) \times B}{2}$$. 5. This is the simplified form of the expression. 6. In plain language, you first subtract 20 from $X$, then divide that result by 2, and finally multiply by $B$. 7. The final answer is: $$\frac{(X - 20)B}{2}$$.