Question

you can use what you learned about exterior angles of triangles to find the value of a.

Explanation:

Step1: Recall exterior - angle property

The exterior angle of a triangle is equal to the sum of the two non - adjacent interior angles.
Let the exterior angle be \(140^{\circ}\), and the two non - adjacent interior angles be \(90^{\circ}\) and \(a\). So, \(140^{\circ}=90^{\circ}+a\).

Step2: Solve for \(a\)

Subtract \(90^{\circ}\) from both sides of the equation: \(a = 140^{\circ}-90^{\circ}\).

Answer:

\(50^{\circ}\)