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Substitution is like replacing the letters in a math expression with numbers. It helps us get rid of the variables and makes the math much easier to handle. In algebra, variables like \(a\), \(b\), or \(c\) act as placeholders representing unknown or changeable numbers. When we substitute, we're simply plugging in actual numbers for these letters.
For example, if we have \(a = 3\) and in the expression \(2a\), substituting \(a\) with 3 transforms the expression into \(2(3)\). This changes an algebraic expression into something we can calculate directly.
Remember, substitution is a key step in many math problems. It simplifies an expression and allows for further calculations. Always begin by substituting known values right at the start to make things clearer as you proceed.

Expression evaluation is about performing calculations once all variables in an expression have been replaced with numbers. It involves going through the expression step-by-step and solving it to find the final value.
After substitution, you're left with a purely numerical expression. The next step is to compute each part of the expression in a logical order. In the problem, once we substitute to get \(2(3) + 2(8)\), we need to evaluate what those multiplications equal first.
Evaluation often involves doing the math operations in the right sequence, usually following the order of operations—parentheses, exponents, multiplication and division (from left to right), and addition and subtraction (from left to right). By carefully evaluating, you ensure accuracy in reaching the right answer.

Mathematical operations are basic actions we perform on numbers. In algebra, these include addition, subtraction, multiplication, and division. When evaluating expressions, it's crucial to operate in the right order.
Let's break down how we used operations in the example expression \(2a + 2b\) after substituting the numbers into it, making it \(2(3) + 2(8)\):

• Multiplication: Perform multiplications first. Calculate \(2 \times 3 = 6\) and \(2 \times 8 = 16\).
• Addition: After finding the products, add the results. Calculate \(6 + 16\) to find the total, which is 22.

Understanding how to use each operation correctly helps not only in math exercises but in solving real-world problems as well. Mastery over these basic operations lays the foundation for tackling more complex concepts in algebra and beyond.