Answer:
b = 39
Step-by-step explanation:
Opposite sides of a parallelogram are congruent to each other. This implies that:
ST = VU
Therefore:
2b - 39 = b (substitution)
2b - 39 - b = 0 (subtraction property of equality)
b - 39 = 0
b = 0 + 39 (addition property of equality)
b = 39
