Question

find the value of x. if necessary, you may learn what the markings on a figure indicate.

Explanation:

Step1: Identify congruent triangles

The two triangles share a side, have one pair of equal sides (marked with ticks) and a pair of right angles, so they are congruent by SAS.

Step2: Find base angles of right triangle

In the right triangle with angle $69^\circ$, the third angle is $90^\circ - 69^\circ = 21^\circ$.

Step3: Use isosceles triangle properties

The left triangle is isosceles (two equal sides), so $x = 90^\circ - 21^\circ = 69^\circ$.

Answer:

$69$