The correct answer to this question is B, 100 units. The word problem helps us find the answer, because we know that QP and TR are parallel. From there, we can know that ST is 30 units. This can be found by adding together QT, 24 units plus SQ, 6 units, which is 30 units.
The question also informs us that SQP is 20 units. With all of this information, the answer can be found with the formula, SQ/ST = PerimiterSQP/PerimiterSTR. Using the numbers provided, the formula becomes 6/30 = 20/PerimiterSTR => PerimiterSTR , which equals the answer of 100 units.