1. Let's start with basic arithmetic operations involving positive and negative numbers. For example, consider the expression $-3 + 7 - 2$. 2. We perform the operations from left to right: first $-3 + 7 = 4$, then $4 - 2 = 2$. So, the result is $2$. 3. Now, let's move to algebraic expressions with variables like $a$, $b$, and $x$. Suppose we have the expression $3a - 2b + 4x$. 4. To simplify or evaluate such expressions, we need values for $a$, $b$, and $x$. For example, if $a=2$, $b=1$, and $x=3$, then substitute these values: $$3(2) - 2(1) + 4(3) = 6 - 2 + 12 = 16$$ 5. When simplifying algebraic expressions, remember to combine like terms (terms with the same variable and exponent) and apply arithmetic operations carefully. 6. For example, simplify $5a + 3b - 2a + 4b$: $$5a - 2a + 3b + 4b = (5 - 2)a + (3 + 4)b = 3a + 7b$$ 7. Always keep track of positive and negative signs, and use parentheses to clarify operations when needed. This covers basic arithmetic with positive and negative numbers and algebraic expressions with variables.