We need to find the values of A and B on the number line, given that adding 5 to A results in 4, and adding 8 to 4 results in B.

1. Problem Description

We need to find the values of A and B on the number line, given that adding 5 to A results in 4, and adding 8 to 4 results in B.

2. Solution Steps

First, let's find the value of A.

We know that $A + 5 = 4$.

To find A, we subtract 5 from both sides of the equation:

$A = 4 - 5$

$A = -1$

Next, let's find the value of B.

We know that $4 + 8 = B$.

So, $B = 12$

3. Final Answer

A = -1

B = 12