1. The problem is to understand and use the delta symbol, often represented as $\Delta$, which means "change in" or "difference in" a quantity. 2. The delta symbol is commonly used in formulas to denote the difference between two values, for example, $\Delta x = x_2 - x_1$ means the change in $x$ from $x_1$ to $x_2$. 3. Important rule: $\Delta$ always represents a subtraction of the initial value from the final value. 4. For example, if $x_1 = 3$ and $x_2 = 7$, then $\Delta x = 7 - 3 = 4$. 5. This concept is used in many areas such as physics for displacement, in calculus for differences, and in algebra for changes in variables. 6. To summarize, whenever you see $\Delta$, think "final minus initial" to find the change in that quantity.