It tells you they are similar. This means the angles are the same, and the sides are proportionate.
Look at the 12 and 4 at the very bottom. This tells you the ratio of the sides. Since 12 / 4 = 3, you can find y with 2 * 3 which is 6.
From that, you also know that 3z = 3y - 2. Substitute the value of y in and you can find z.
Corresponding angles are exactly the same. which means, (3x)° = 100°
You should get x = 33 1/3, y = 6, z = 5 1/3
