Question

x = (5x + 9)° (8x - 30)°

Explanation:

Step1: Identify triangle property

The triangle is isosceles as two sides are equal, so the base - angles are equal. We set up the equation based on the equality of the two given angle - expressions.
$5x + 9=8x - 30$

Step2: Rearrange terms to solve for x

Subtract $5x$ from both sides:
$5x+9 - 5x=8x - 30-5x$
$9 = 3x-30$
Then add 30 to both sides:
$9 + 30=3x-30 + 30$
$39 = 3x$

Step3: Solve for x

Divide both sides by 3:
$\frac{39}{3}=\frac{3x}{3}$
$x = 13$

Answer:

$x = 13$