# Practice Math Questions for Praxis: Solving Expressions with Given Values

Some questions on the Praxis Core exam involve a simple plug-and-play approach, where you solve an expression by substituting given values for the variables. Sounds easy, right?

Well, yes and no: as you’ll see in the following practice questions, you still need to watch out for double negatives and you have to know your order of operations.

## Practice questions

- What is the value of this expression if
*x*= 1,*y*= –5,*z*= 8?7

*x*– 5*y*+ 4*z***A.**–8

**B.**103

**C.**64

**D.**36

**E.**–71 - What is the value of this expression if
*k*= –7,*m*= –10, and*n*= 11?

## Answers and explanations

- The correct answer is Choice
**(C).**Substitute each variable value in for its corresponding variable. Then simplify the result.

- The correct answer is Choice
**(C).**You can substitute each variable value in for its corresponding variable and then simplify the resulting rational expression: