−<span>3<span>(<span><span>4a</span>−<span>5b</span></span>)</span></span><span>=<span><span>(<span>−3</span>)</span><span>(<span><span>4a</span>+<span>−<span>5b</span></span></span>)</span></span></span><span>=<span><span><span>(<span>−3</span>)</span><span>(<span>4a</span>)</span></span>+<span><span>(<span>−3</span>)</span><span>(<span>−<span>5b</span></span>)</span></span></span></span><span>=<span><span>−<span>12a</span></span>+<span>15<span>b</span></span></span></span>
we are given

we can solve for x
We can isolate x
step-1: Multiply both sides by b/a


step-2:Add 12 both sides


step-3: combine right side

step-4:Divide both sides by 2
..............Answer
The base angles of an isosceles triangle are equal
The base angles are 15 degrees, while the vertex angle is 150 degrees
The base angles are given as:
Base = (6a- 3) and (a + 12)
So, we have:

Collect like terms


Divide both sides by 5

Substitute 3 for a in Base = (6a- 3),



So, the base angle is 15 degrees.
The vertex angle is calculated using:

So, we have:


Hence, the vertex angle is 150 degrees
Read more about isosceles triangles at:
brainly.com/question/25739654