Since B is the midpoint of AC, AB =BC. So, BC=3x

3x + 4 = 2x + 12

-4 -4  Subtraction Property of Equality

3x = 2x + 8

-2x -2x  Subtraction Property of Equality

x = 8

So your answer for x is 8

Step-by-step explanation:

3< x< 5

step-by-step explanation:

|x - 4| < 1

there are two solutions, one positive and one negative.   remember to flip the inequality when taking the negative solution

x-4 < 1       x-4 > -1

add 4 to each side

x-4+4 < 1+4       x-4+4 > -1+4

x< 5                 x> 3

3< x< 5