Lesson Steps:

8 = 4 + x
Step 1: Move like variables to one side. Isolate x.
                     8 - 4 = x

Since we're moving 4, that was a positive number, to the other side, change it's sign to negative.

Step 2: Evaluate (8 - 4)

                     4 = x

Hence, we get x = 4.

Answer:

x = 4

Grade: 7
Level: Primary
Subject: Math
Topic: Algebra