Find the value of angle b.

Step 1: Find the value of angle $b$. Angle $b$ is an exterior angle of the triangle. The exterior angle of a triangle is equal to the sum of the two opposite interior angles. The two opposite interior angles are $73^\circ$ and $35^\circ$. $b = 73^\circ + 35^\circ$ $b = 108^\circ$

Step 2: Find the value of angle $a$. Angle $a$ and angle $b$ form a linear pair on a straight line. The sum of angles on a straight line is $180^\circ$. $a + b = 180^\circ$ Substitute the value of $b$ found in Step 1: $a + 108^\circ = 180^\circ$ $a = 180^\circ - 108^\circ$ $a = 72^\circ$

The angles are: $a=72^\circ, b=108^\circ$ That's 2 down. 3 left today — send the next one.