Given that |ST| = |SR| and m TSR = 70^, TSR is an isosceles triangle. In an isosceles triangle, the base angles opposite the equal sides are equal.

Step 1: Identify the properties of triangle $\triangle TSR$.
Given that $|ST| = |SR|$ and $m\angle TSR = 70^\circ$, $\triangle TSR$ is an isosceles triangle. In an isosceles triangle, the base angles opposite the equal sides are equal.
The sum of angles in a triangle is $180^\circ$.

$$m\angle STR + m\angle SRT + m\angle TSR = 180^\circ$$

Since $m\angle STR = m\angle SRT$:

$$2 \cdot m\angle SRT + 70^\circ = 180^\circ$$ $$2 \cdot m\angle SRT = 180^\circ - 70^\circ$$