what is the value of b?

Explanation:

Step1: Identify angle - relationship

The two angles (b) and (60^{\circ}) are complementary (since the right - angle symbol is shown, meaning the sum of the two non - right angles is (90^{\circ})).

Step2: Set up equation

We know that (b + 60^{\circ}=90^{\circ}).

Step3: Solve for (b)

Subtract (60^{\circ}) from both sides of the equation: (b=90^{\circ}- 60^{\circ}).

Answer:

(30^{\circ})