Question

solve for x.
5)

Explanation:

Step1: Use exterior - angle property

The exterior - angle of a triangle is equal to the sum of the two non - adjacent interior angles. So, $12x + 12=( - 2+4x)+78$.

Step2: Simplify the right - hand side

Combine like terms on the right - hand side: $12x + 12=4x+76$.

Step3: Move terms with x to one side

Subtract $4x$ from both sides: $12x-4x + 12=4x-4x + 76$, which gives $8x+12 = 76$.

Step4: Isolate the term with x

Subtract 12 from both sides: $8x+12 - 12=76 - 12$, so $8x=64$.

Step5: Solve for x

Divide both sides by 8: $\frac{8x}{8}=\frac{64}{8}$, so $x = 8$.

Answer:

$x = 8$