Integer addition and subtraction with substitution

The  exercise appears under the 7th grade (U.S.) Math Mission. This exercise practices.

Types of Problems
There is one type of problem in this exercise:
 * 1. Evaluate: This problem has an equation with variables and negative numbers. The student is asked to evaluate the answer of the equation.

Strategies
Knowledge of adding and subtracting negative numbers are essential to ensure success in this exercise.
 * 1. Number lines are useful for adding and subtracting negative numbers.