Solve the following.

In ABC, AB = CB, mABC = 4x - 3, and mCAB = x - 3. What is mACB?

A. 28.5°

B. 31.5°

C. 63°

D. 34.5°

The correct answer to this question is this one: "A. 28.5°"

Since AB = CB,

then, there are two angles that are the same:

angle CAB and angle ACB.

We need to get the value of x

4x - 3 + 2 (x - 3) = 180

4x - 3 + 2x - 6 = 180

6x - 9 = 180

6x = 189

x = 31.5

So angle ACB would be,

mACB = x - 3

mACB = 31.5 - 3

mACB = 28.5