GED Math Extra Prep: Value Substitution

By Consumer Dummies

Value substitution questions on the GED Math test are fairly straightforward: they ask you to substitute actual numbers for variables in an expression and find the answer. The important thing to remember here is order of operations, or PEMDAS.

Practice Questions

  1. What is the value of 6x – 3y2 when x = 12 and y = –5?

    A. –153
    B. 297
    C. –3
    D. 147

    The next question is based on the following information.


  2. Which of the following expresses


    in terms of p?

    A. 0
    B. 1
    C. p–5
    D. p

Answers and Explanations

  1. The correct answer is C.

    Substitute the given values of x and y into the expression:

    6x – 3y2 = 6(12) – 3(–5)2

    Then use the correct order of operations to simplify: Remember PEMDAS — (Parentheses, then Exponents, then Multiplication and Division, and then Addition and Subtraction). So first evaluate the exponent, then perform the multiplication, and finally perform the subtraction:


    Hence, Choice (C) is correct.

  2. The correct answer is B.

    Any expression to the power zero equals 1. Hence, the correct answer is Choice (B).