Answer
m$\angle$ RST = 42$^{\circ}$
Work Step by Step
Using the Segment Addition Postulate:
m$\angle$RST + m$\angle$TSV = m$\angle$RSV
Substitute in the values from the problem.
m$\angle$RST + 17 = 59
Subtract 17 from both sides of the equation
m$\angle$RST + 17 - 17= 59 - 17
m$\angle$RST = 42