Answer:
The measure of the two smaller angles i.e ∠RSU = ∠UST = 40° .
Explanation:
As given
∠RST measures 80 degrees.
Ray SU bisects the angle.
Divided anything in two equal part is called bisect .
i.e SU bisect the ∠RST into two equal parts .
As the diagram is given below.
Thus

∠RSU = ∠UST = 40°
Therefore the measure of the two smaller angles i.e ∠RSU = ∠UST = 40° .