The calculated measure of the angle SRT is 138 degrees
How to determine the measure of the angle SRT
From the question, we have the following parameters that can be used in our computation:
The rhombus
Where, we have
RST = 42 degrees
The adjacent angles of a rhombus are supplementary
This means that
SRT = 180 - RST
SRT = 180 - 42 degrees
Evaluate
SRT = 138 degrees
Hence, the measure of the angle SRT is 138 degrees